Occlusion detection techniques for a fluid infusion device having a rotary pump mechanism and rotor position sensors

ABSTRACT

An embodiment of a fluid infusion device includes a fluid pump mechanism having a rotor and a stator. The rotor includes a reference surface and a cam element rising from the reference surface, and the stator includes a cam element having a stator cam surface. The cam elements cooperate to axially displace the rotor as a function of angular position of the rotor. A biasing element provides force to urge the cam elements together. A drive motor actuates the rotor to pump medication fluid from a fluid cartridge module to a body, via a subcutaneous conduit. A detection circuit processes axial and angular position data of the rotor, and determines that an upstream occlusion has occurred based on detectable characteristics of the axial and angular position data.

TECHNICAL FIELD

Embodiments of the subject matter described herein relate generally tofluid infusion devices of the type suitable for delivering a medicationfluid to the body of a patient. More particularly, embodiments of thesubject matter presented herein relate to techniques for detecting anocclusion in the fluid delivery path of a fluid infusion device having arotary pump mechanism.

BACKGROUND

Certain diseases or conditions may be treated, according to modernmedical techniques, by delivering a medication fluid or other substanceto the body of a patient, either in a continuous manner or at particulartimes or time intervals within an overall time period. For example,diabetes is commonly treated by delivering defined amounts of insulin tothe patient at appropriate times. Some common modes of providing insulintherapy to a patient include delivery of insulin through manuallyoperated syringes and insulin pens. Other modern systems employprogrammable fluid infusion devices (e.g., insulin pumps) to delivercontrolled amounts of insulin to a patient.

A fluid infusion device suitable for use as an insulin pump may berealized as an external device or an implantable device, which issurgically implanted into the body of the patient. External fluidinfusion devices include devices designed for use in a generallystationary location (for example, in a hospital or clinic bedsideenvironment), and devices configured for ambulatory or portable use (tobe carried or worn by a patient). External fluid infusion devices mayestablish a fluid flow path from a fluid reservoir or cartridge to thepatient via, for example, a suitable hollow tubing, needle, or othertype of fluid conduit.

A fluid infusion device can be implemented with a rotary micropumpmechanism that accurately delivers a precise volume of fluid with eachrevolution or cycle. The inlet of the micropump is connected to a fluidsource such as a reservoir, and the outlet of the micropump is connectedto a fluid delivery conduit that leads to the body of the patient. Undernormal operating conditions, the micropump draws fluid from the fluidsource (via a vacuum or suction action) and then delivers a predictablevolume of fluid with each cycle.

It is desirable to reliably and accurately detect at least twoconditions, for purposes of alerting the user and/or to otherwisecontrol the operation of the fluid infusion device in a responsivemanner. One of these “fault” conditions is a downstream occlusion in thefluid delivery path (e.g., a blockage downstream from the outlet of themicropump). Another “fault” condition is an upstream occlusion (e.g., ablockage located before the inlet of the micropump). In this regard, anempty fluid reservoir can be considered to be an upstream occlusionbecause continued operation of the micropump in the presence of an emptyreservoir does not result in the normally expected delivery of fluid.

Accordingly, it is desirable to have a fluid infusion device and relatedoperating methodologies that effectively detect upstream and/ordownstream occlusions in the fluid delivery pathway associated with arotary micropump. In addition, it is desirable to provide an improvedrotary micropump having certain features and functionality thatfacilitate the detection of upstream and/or downstream occlusions in thefluid delivery pathway. Furthermore, other desirable features andcharacteristics will become apparent from the subsequent detaileddescription and the appended claims, taken in conjunction with theaccompanying drawings and the foregoing technical field and background.

BRIEF SUMMARY

Various upstream and downstream occlusion detection techniques andmethodologies are disclosed herein. The occlusion detection techniquesand methodologies can be implemented in a fluid infusion device thatincludes a rotary fluid pump mechanism (having a rotor and a stator).Actuation of the fluid pump mechanism draws fluid from a fluid reservoirduring an intake stroke and expels the fluid during a delivery stroke.

In accordance with certain embodiments, the fluid pump mechanismincludes a stator having a fluid chamber defined therein, and alsohaving a stator cam element with a stator cam surface. The fluid pumpmechanism also includes a rotor having an endcap with a referencesurface, an axial extension section protruding from the endcap, whereinat least a portion of the axial extension section fits inside the fluidchamber, and a rotor cam element having a variable height rising fromthe reference surface. The rotor cam element cooperates with the statorcam element to axially displace the rotor, relative to the stator, as afunction of angular position of the rotor. A sensor contact elementresides on the reference surface and is located in an area that isunoccupied by the rotor cam element. A sensing element terminates at ornear the stator cam surface. The sensing element cooperates with adetection circuit to detect whether or not the stator cam surface is incontact with the sensor contact element. The detection circuit monitorscharacteristics of a detection signal obtained from the sensing elementin response to angular position of the rotor to determine an operatingcondition of the fluid pump mechanism.

Also presented here is an exemplary embodiment of a fluid infusiondevice for delivering a medication fluid to a body. The fluid infusiondevice includes a fluid pump mechanism that cooperates with a fluidcartridge module. The fluid pump mechanism has a rotor and a stator,wherein the rotor includes a reference surface and a rotor cam elementhaving a variable height rising from the reference surface. The statorincludes a stator cam element having a stator cam surface, wherein therotor cam element cooperates with the stator cam element to axiallydisplace the rotor, relative to the stator, as a function of angularposition of the rotor. The fluid infusion device also includes asubcutaneous conduit in fluid communication with an outlet valve of thefluid pump mechanism, and a drive motor coupled to actuate the rotor ofthe fluid pump mechanism to pump medication fluid from the fluidcartridge module to the body, via the subcutaneous conduit. A sensorcontact element is provided on the reference surface of the rotor. Thesensor contact element is located in an area that is unoccupied by therotor cam element. A sensing element terminates at or near the statorcam surface. The sensing element cooperates with a detection circuit todetect whether or not the stator cam surface is in contact with thesensor contact element. The detection circuit monitors characteristicsof a detection signal obtained from the sensing element in response toangular position of the rotor to determine an operating condition of thefluid pump mechanism.

An exemplary embodiment of a fluid pump mechanism is also presentedhere. The fluid pump mechanism includes: a stator; a rotor; an inletvalve that opens and closes as a function of angular and axial positionof the rotor; an outlet valve that opens and closes as a function ofangular and axial position of the rotor; a sensor contact element; and asensing element. The stator cam element has a stator cam surface, andthe rotor includes a reference surface and a rotor cam element having avariable height rising from the reference surface. The rotor cam elementcooperates with the stator cam element to axially displace the rotor,relative to the stator, as a function of angular position of the rotor.The sensor contact element resides on the reference surface in an areacorresponding to a valve state in which the inlet valve is closed andthe outlet valve is open. The sensing element terminates at or near thestator cam surface, and it cooperates with a detection circuit to detectwhether or not the stator cam surface is in contact with the sensorcontact element. The detection circuit monitors characteristics of adetection signal obtained from the sensing element in response toangular position of the rotor to determine an operating condition of thefluid pump mechanism.

Another exemplary embodiment of a fluid pump mechanism employs a forcesensor to detect occlusions in the fluid path. The fluid pump mechanismincludes a stator with a stator cam element having a stator cam surface.The fluid pump mechanism also includes a rotor with a reference surfaceand a rotor cam element having a variable height rising from thereference surface. The rotor cam element cooperates with the stator camelement to axially displace the rotor, relative to the stator, as afunction of angular position of the rotor. A biasing element provides abiasing force to urge the rotor cam element toward the stator camelement and toward the reference surface. A force sensor is coupled tothe rotor. The force sensor generates output levels in response to forceimparted thereto, and the force sensor cooperates with a detectioncircuit that obtains and processes the output levels to detectocclusions in a fluid path downstream of the fluid pump mechanism.

An exemplary embodiment of a fluid infusion device includes a fluid pumpmechanism that cooperates with a fluid cartridge module. The fluid pumpmechanism has a rotor and a stator. The rotor includes a referencesurface and a rotor cam element having a variable height rising from thereference surface. The stator includes a stator cam element having astator cam surface, wherein the rotor cam element cooperates with thestator cam element to axially displace the rotor, relative to thestator, as a function of angular position of the rotor. A biasingelement provides a biasing force to urge the rotor cam element towardthe stator cam element and toward the reference surface. The fluidinfusion device also includes a subcutaneous conduit in fluidcommunication with an outlet valve of the fluid pump mechanism, and adrive motor coupled to actuate the rotor of the fluid pump mechanism topump medication fluid from the fluid cartridge module to the body, viathe subcutaneous conduit. A force sensor is coupled to the rotor togenerate output levels in response to force imparted thereto. The forcesensor cooperates with a detection circuit that obtains and processesthe output levels to detect occlusions in a fluid path downstream of thefluid pump mechanism.

An exemplary embodiment of a fluid infusion device includes a statorwith a stator cam element having a stator cam surface, and a rotor witha reference surface and a rotor cam element having a variable heightrising from the reference surface. The rotor cam element cooperates withthe stator cam element to axially displace the rotor, relative to thestator, as a function of angular position of the rotor. A biasingelement provides a biasing force to urge the rotor cam element towardthe stator cam element and toward the reference surface. The fluidinfusion device also includes an inlet valve that opens and closes as afunction of angular and axial position of the rotor, and an outlet valvethat opens and closes as a function of angular and axial position of therotor. A force sensor is coupled to the rotor to generate output levelsin response to force imparted thereto. A detection circuit cooperateswith the force sensor to obtain and process the output levels of theforce sensor to detect occlusions in a fluid path downstream of thefluid pump mechanism.

In accordance with other exemplary embodiments, a fluid pump mechanismincludes a stator with a stator cam element having a stator cam surface,and a rotor with an optically detectable feature, a reference surface,and a rotor cam element having a variable height rising from thereference surface. The rotor cam element cooperates with the stator camelement to axially displace the rotor, relative to the stator, as afunction of angular position of the rotor. The optically detectablefeature rotates and axially translates as a function of angular positionof the rotor. An optical detection circuit interrogates the opticallydetectable feature during operation of the fluid pump mechanism todetermine an operating condition of the fluid pump mechanism.

An exemplary embodiment of a fluid infusion device includes a fluid pumpmechanism that cooperates with a fluid cartridge module. The fluid pumpmechanism includes a rotor and a stator, wherein the rotor has anoptically detectable feature, a reference surface, and a rotor camelement having a variable height rising from the reference surface. Thestator includes a stator cam element having a stator cam surface, suchthat the rotor cam element cooperates with the stator cam element toaxially displace the rotor, relative to the stator, as a function ofangular position of the rotor. The optically detectable feature rotatesand axially translates as a function of angular position of the rotor,and a biasing element provides a biasing force to urge the rotor camelement toward the stator cam element and toward the reference surface.The fluid infusion device also includes: a subcutaneous conduit in fluidcommunication with an outlet valve of the fluid pump mechanism; a drivemotor coupled to actuate the rotor of the fluid pump mechanism to pumpmedication fluid from the fluid cartridge module to the body, via thesubcutaneous conduit; and an optical detection circuit to interrogatethe optically detectable feature during operation of the fluid pumpmechanism to determine an operating condition of the fluid pumpmechanism.

An exemplary embodiment of a fluid infusion device includes a statorwith a stator cam element having a stator cam surface, and includes arotor with an optically detectable feature, a reference surface, and arotor cam element having a variable height rising from the referencesurface. The rotor cam element cooperates with the stator cam element toaxially displace the rotor, relative to the stator, as a function ofangular position of the rotor. An inlet valve opens and closes as afunction of angular and axial position of the rotor, and an outlet valveopens and closes as a function of angular and axial position of therotor. An optical detection circuit cooperates with the opticallydetectable feature, wherein the optical detection circuit interrogatesthe optically detectable feature to determine an operating condition ofthe fluid infusion device.

In accordance with certain exemplary embodiments, a fluid pump mechanismincludes a stator with a stator cam element having a stator cam surface,and a rotor with a reference surface and a rotor cam element having avariable height rising from the reference surface. The rotor cam elementcooperates with the stator cam element to axially displace the rotor,relative to the stator, as a function of angular position of the rotor.A biasing element provides a biasing force to urge the rotor cam elementtoward the stator cam element and toward the reference surface. Adetection circuit processes axial and angular position data of therotor, and determines that an upstream occlusion has occurred based ondetectable characteristics of the axial and angular position data.

An exemplary embodiment of a fluid infusion device includes: a fluidpump mechanism; a biasing element; a subcutaneous conduit; a drivemotor; and a detection circuit. The fluid pump mechanism cooperates witha fluid cartridge module, and the fluid pump mechanism includes a rotorand a stator. The rotor includes a reference surface and a rotor camelement having a variable height rising from the reference surface, andthe stator includes a stator cam element having a stator cam surface.The rotor cam element cooperates with the stator cam element to axiallydisplace the rotor, relative to the stator, as a function of angularposition of the rotor. The biasing element provides a biasing force tourge the rotor cam element toward the stator cam element and toward thereference surface. The subcutaneous conduit is in fluid communicationwith an outlet valve of the fluid pump mechanism. The drive motor iscoupled to actuate the rotor of the fluid pump mechanism to pumpmedication fluid from the fluid cartridge module to the body, via thesubcutaneous conduit. The detection circuit processes axial and angularposition data of the rotor, and determines that an upstream occlusionhas occurred based on detectable characteristics of the axial andangular position data.

An exemplary embodiment of a fluid infusion device includes a statorwith a stator cam element having a stator cam surface, and a rotor witha reference surface and a rotor cam element having a variable heightrising from the reference surface. The rotor cam element cooperates withthe stator cam element to axially displace the rotor, relative to thestator, as a function of angular position of the rotor. A biasingelement provides a biasing force to urge the rotor cam element towardthe stator cam element and toward the reference surface. An axialposition sensor obtains axial position data of the rotor, and an angularposition sensor obtains angular position data of the rotor. A detectioncircuit obtains and processes the axial position data and the angularposition data, wherein the detection circuit determines that an upstreamocclusion has occurred based on processing of the axial position dataand the angular position data.

In accordance with other exemplary embodiments, a fluid pump mechanismincludes a stator with a stator cam element having a stator cam surface,and a rotor with a reference surface and a rotor cam element having avariable height rising from the reference surface. The rotor cam elementcooperates with the stator cam element to axially displace the rotor,relative to the stator, as a function of angular position of the rotor.The fluid pump mechanism also includes an inlet valve that opens andcloses as a function of angular and axial position of the rotor relativeto the stator, and an outlet valve that opens and closes as a functionof angular and axial position of the rotor relative to the stator. Abiasing element provides a biasing force to urge the rotor toward thestator. A first sensor contact element resides on the rotor and islocated at an angular position that follows an upper edge of the rotorcam element. A second sensor contact element resides on the rotor and islocated at an angular position that follows the first sensor contactelement. A sensing element resides on the stator, wherein the sensingelement cooperates with a detection circuit to detect when the sensingelement makes contact with the first sensor contact element and thesecond sensor contact element. The detection circuit monitorscharacteristics of a detection signal obtained from the sensing elementin response to angular position of the rotor to determine an operatingcondition of the fluid pump mechanism.

An exemplary embodiment of a fluid infusion device includes a fluid pumpmechanism that cooperates with a fluid cartridge module. The fluid pumpmechanism includes a rotor and a stator; the rotor has a referencesurface and a rotor cam element having a variable height rising from thereference surface. The stator includes a stator cam element having astator cam surface, wherein the rotor cam element cooperates with thestator cam element to axially displace the rotor, relative to thestator, as a function of angular position of the rotor. An inlet valveopens and closes as a function of angular and axial position of therotor relative to the stator, and an outlet valve opens and closes as afunction of angular and axial position of the rotor relative to thestator. A biasing element provides a biasing force to urge the rotortoward the stator. A subcutaneous conduit is in fluid communication withthe outlet valve, and drive motor is coupled to actuate the rotor of thefluid pump mechanism to pump medication fluid from the fluid cartridgemodule to the body, via the subcutaneous conduit. A first sensor contactelement resides on the rotor and is located at an angular position thatfollows an upper edge of the rotor cam element. A second sensor contactelement resides on the rotor and is located at an angular position thatfollows the first sensor contact element. A sensing element resides onthe stator, and it cooperates with a detection circuit to detect whenthe sensing element makes contact with the first sensor contact elementand the second sensor contact element. The detection circuit monitorscharacteristics of a detection signal obtained from the sensing elementin response to angular position of the rotor to determine an operatingcondition of the fluid pump mechanism.

An exemplary embodiment of a fluid pump mechanism includes a stator witha stator cam element having a stator cam surface. The fluid pumpmechanism also includes a rotor having: an endcap with a rim; areference surface located inside the endcap; and a rotor cam elementlocated inside the endcap and having a variable height rising from thereference surface. The rotor cam element cooperates with the stator camelement to axially displace the rotor, relative to the stator, as afunction of angular position of the rotor. A first sensor contactelement resides on the rim of the endcap, and is located at an angularposition that follows an upper edge of the rotor cam element. A secondsensor contact element resides on the rim of the endcap, and is locatedat an angular position that follows the first sensor contact element. Abiasing element provides a biasing force to urge the rotor toward thestator. The fluid pump mechanism also includes: an inlet valve thatopens and closes as a function of angular and axial position of therotor relative to the stator; an outlet valve that opens and closes as afunction of angular and axial position of the rotor relative to thestator; and a sensing element that cooperates with a detection circuitto detect when the sensing element makes contact with the first sensorcontact element and the second sensor contact element. The detectioncircuit monitors characteristics of a detection signal obtained from thesensing element to determine an operating condition of the fluid pumpmechanism.

This summary is provided to introduce a selection of concepts in asimplified form that are further described below in the detaileddescription. This summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used as an aid in determining the scope of the claimed subjectmatter.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the subject matter may be derived byreferring to the detailed description and claims when considered inconjunction with the following figures, wherein like reference numbersrefer to similar elements throughout the figures.

FIG. 1 is a top perspective view of an embodiment of a fluid infusiondevice implemented as a patch pump device;

FIG. 2 is a perspective view that depicts the insertion of the removablefluid cartridge module into the fluid infusion device;

FIG. 3 is a perspective view that shows certain internal components ofthe fluid infusion device;

FIG. 4 is a block diagram representation of the system architecture of afluid infusion device according to certain embodiments;

FIGS. 5-8 are diagrams that depict a fluid pump mechanism in variousstages during one pump cycle;

FIG. 9 is an exploded perspective view of a stator and a rotor of anexemplary embodiment of a fluid pump mechanism;

FIG. 10 is a perspective view of an exemplary embodiment of a stator ofa fluid pump mechanism;

FIG. 11 is a perspective view of an exemplary embodiment of a rotor of afluid pump mechanism;

FIGS. 12-14 are diagrams that depict the cooperation between a statorcam element and a rotor cam element of a fluid pump mechanism;

FIG. 15 is a graph that includes a plot of rotor axial position versusrotor angular position;

FIG. 16 is a graph that includes a plot of rotor axial position versusrotor angular position for a downstream occlusion condition;

FIG. 17 is an end view of an exemplary embodiment of a rotor of a fluidpump mechanism;

FIG. 18 is an end view of an exemplary embodiment of a stator of a fluidpump mechanism;

FIG. 19 is a diagram that depicts the stator shown in FIG. 18cooperating with a detection circuit;

FIG. 20 is a schematic block diagram that illustrates an exemplaryembodiment of an occlusion detection system suitable for use with afluid infusion device;

FIG. 21 is a simplified diagram of an exemplary embodiment of an opticalor acoustic based occlusion detection system suitable for use with afluid infusion device;

FIG. 22 is a simplified diagram of an exemplary embodiment of anocclusion detection system that utilizes position sensing techniques;

FIG. 23 is a simplified perspective view of an exemplary embodiment of arotor of a fluid pump mechanism;

FIG. 24 is a simplified diagram of an exemplary embodiment of anocclusion detection system that utilizes a potentiometer as a sensingelement;

FIG. 25 is a simplified diagram of an exemplary embodiment of anocclusion detection system that utilizes an electrical contact as adigital switch;

FIG. 26 is a simplified end view of a stator having an electricallyconductive rim;

FIG. 27 is a simplified diagram of an exemplary embodiment of anocclusion detection system that cooperates with the stator shown in FIG.26;

FIG. 28 is a simplified diagram of an exemplary embodiment of anocclusion detection system that utilizes a force sensor;

FIG. 29 is a simplified diagram of an exemplary embodiment of anocclusion detection system that utilizes optical sensing technology;

FIG. 30 is a simplified perspective view of an exemplary embodiment of arotor having physical features that cooperate with an optical detectioncircuit;

FIG. 31 is a side view of a section of the rotor shown in FIG. 30;

FIG. 32 is a simplified diagram of an exemplary embodiment of an end ofreservoir detection system interrogating a fluid reservoir;

FIG. 33 is a simplified diagram of the end of reservoir detection systemdetecting an empty reservoir condition;

FIG. 34 is a simplified diagram of an exemplary embodiment of an end ofreservoir detection system that implements a mechanical switch concept;

FIG. 35 is a simplified diagram of an exemplary embodiment of an end ofreservoir detection system that utilizes a conductive fluid reservoirstopper (or a conductive element of a stopper);

FIG. 36 is a simplified diagram of an exemplary embodiment of an end ofreservoir detection system that applies an excitation signal to a fluidreservoir;

FIG. 37 is a simplified diagram of an exemplary embodiment of an end ofreservoir detection system that uses a force sensor to determine theposition of a stopper of a fluid reservoir;

FIG. 38 is a simplified diagram of an exemplary embodiment of an end ofreservoir detection system that uses a pressure sensor to determine theposition of a stopper of a fluid reservoir;

FIG. 39 is a simplified diagram of an exemplary embodiment of an end ofreservoir detection system that measures an inductance to determine theposition of a stopper of a fluid reservoir;

FIG. 40 is a simplified diagram of an exemplary embodiment of an end ofreservoir detection system that measures a capacitance to determine theposition of a stopper of a fluid reservoir;

FIG. 41 is a schematic block diagram of an exemplary embodiment of anend of reservoir detection system that measures axial velocity of arotor of a fluid pump mechanism;

FIG. 42 is a graph that includes a plot of rotor axial position versusrotor angular position for an upstream occlusion condition;

FIG. 43 is a graph that includes plots of rotor axial position versusrotor angular position for various operating conditions of a fluid pumpmechanism;

FIG. 44 is a perspective view of an exemplary embodiment of a rotor of afluid pump mechanism;

FIG. 45 is a perspective end view of another exemplary embodiment of arotor of a fluid pump mechanism; and

FIG. 46 is a side view that depicts the rotor of FIG. 45 cooperatingwith a stator.

DETAILED DESCRIPTION

The following detailed description is merely illustrative in nature andis not intended to limit the embodiments of the subject matter or theapplication and uses of such embodiments. As used herein, the word“exemplary” means “serving as an example, instance, or illustration.”Any implementation described herein as exemplary is not necessarily tobe construed as preferred or advantageous over other implementations.Furthermore, there is no intention to be bound by any expressed orimplied theory presented in the preceding technical field, background,brief summary or the following detailed description.

Certain terminology may be used in the following description for thepurpose of reference only, and thus are not intended to be limiting. Forexample, terms such as “upper”, “lower”, “above”, and “below” could beused to refer to directions in the drawings to which reference is made.Terms such as “front”, “back”, “rear”, “side”, “outboard”, and “inboard”could be used to describe the orientation and/or location of portions ofthe component within a consistent but arbitrary frame of reference whichis made clear by reference to the text and the associated drawingsdescribing the component under discussion. Such terminology may includethe words specifically mentioned above, derivatives thereof, and wordsof similar import. Similarly, the terms “first”, “second”, and othersuch numerical terms referring to structures do not imply a sequence ororder unless clearly indicated by the context.

The following description relates to a fluid infusion device of the typeused to treat a medical condition of a patient. The infusion device isused for infusing fluid (such as a medication) into the body of a user.The non-limiting examples described below relate to a medical deviceused to treat diabetes (more specifically, an insulin infusion device),although embodiments of the disclosed subject matter are not so limited.Accordingly, the infused medication fluid is insulin in certainembodiments. In alternative embodiments, however, many other fluids maybe administered through infusion such as, but not limited to, diseasetreatments, drugs to treat pulmonary hypertension, iron chelation drugs,pain medications, anti-cancer treatments, medications, vitamins,hormones, or the like. For the sake of brevity, conventional featuresand characteristics related to infusion system operation, insulin pumpoperation, fluid reservoirs, and fluid conduits such as soft cannulasmay not be described in detail here.

General Overview And System Architecture

FIG. 1 is a top perspective view of an embodiment of a fluid infusiondevice 100 implemented as a patch pump device, FIG. 2 is a perspectiveview that depicts the insertion of a removable fluid cartridge module104 into the fluid infusion device 100, and FIG. 3 is a perspective viewthat shows certain internal components of the fluid infusion device 100.The removable fluid cartridge module 104 is designed and configured forcompatibility with the fluid infusion device 100, and FIG. 1 shows thefluid cartridge module 104 installed and secured within the fluidinfusion device 100. The figures depict one possible configuration andform factor of the fluid infusion device 100. It should be appreciatedthat other designs and configurations can be utilized if so desired, andthat the particular design aspects shown in the figures are not intendedto limit or otherwise restrict the scope or application of theembodiments described herein.

The fluid infusion device 100 includes a housing 106 that serves as ashell for a variety of internal components. The housing 106 is suitablyconfigured to receive, secure, and release the removable fluid cartridgemodule 104. In this regard, the fluid cartridge module 104 can bereceived in a suitably shaped, sized, and configured cavity that isdesigned in accordance with certain physical characteristics of thefluid cartridge module 104. For example, the housing 106 can includestructural features that mate with or otherwise engage structuralfeatures of the fluid cartridge module 104. The illustrated embodimentof the removable fluid cartridge module 104 includes a retentionmechanism 110 that secures the fluid cartridge module 104 in theproperly installed and seated position within the fluid infusion device100. The retention mechanism 110 locks the fluid cartridge module 104 inplace within the cavity 108 to maintain the necessary physical and fluidconnections between the fluid cartridge module 104 and the fluidinfusion device 100. The retention mechanism 110 can be physicallymanipulated to release the fluid cartridge module 104 from the housing106 as needed (e.g., to replace one cartridge module with a differentcartridge module, to remove the cartridge module when replacing an oldfluid infusion device with a new fluid infusion device, or the like). Inpractice, the retention mechanism 110 can be realized as a latchingfeature, a locking feature, a tab, or the like.

The fluid infusion device 100 includes at least one user interfacefeature, which can be actuated by the patient as needed. The illustratedembodiment of the fluid infusion device 100 includes a button 112 thatis physically actuated. The button 112 can be a multipurpose userinterface if so desired to make it easier for the user to operate thefluid infusion device 100. In this regard, the button 112 can be used inconnection with one or more of the following functions, withoutlimitation: waking up the processor and/or electronics of the fluidinfusion device 100; triggering an insertion mechanism for actuating atranscutaneous conduit assembly (e.g., inserting a cannula into thesubcutaneous space, or similar region of the patient); configuring oneor more settings of the fluid infusion device 100; initiating deliveryof medication fluid; initiating a fluid priming operation; disablingalerts or alarms generated by the fluid infusion device 100; and thelike. In lieu of the button 112, the fluid infusion device 100 canemploy a slider mechanism, a pin, a lever, or the like.

The fluid infusion device 100 includes an adhesive element or adhesivematerial (hidden from view in FIG. 1 and FIG. 2) that can be used toaffix the housing 106 to the body of the patient. The adhesive elementcan be located on the bottom surface of the housing 106 such that thehousing 106 can be temporarily adhered to the skin of the patient. Theadhesive element may be, for example, a piece of double sided adhesivetape that is cut into the desired shape and size. The fluid infusiondevice 100 is manufactured with an adhesive liner overlying the adhesiveelement; the adhesive liner is peeled away to expose the sticky surfaceof the adhesive element 114. The adhesive element is chosen to be strongenough to maintain the fluid infusion device 100 in place for thedesired period of time (which is typically between one to seven days)and strong enough to withstand typical use cases (e.g., showering, rainydays, physical exercise, etc.), while also being easy to remove withoutdiscomfort.

Setup and operation of the fluid infusion device 100 is simple andstraightforward for the patient. In this regard, the particularprocedure for setup and initiation may vary from one embodiment toanother, depending on the specific configuration, design, form factor,and/or optional settings of the fluid infusion device 100. In accordancewith one high level method of operation, the fluid infusion device 100is deployed in the following manner: (1) insert the fluid cartridgemodule 104 into the housing 106; (2) remove the adhesive liner; (3)affix the housing 106 to the body; and (4) insert the fluid deliverycannula into the body by pressing a button, pulling a tab, removing asafety pin, or otherwise activating an insertion mechanism to release apreloaded spring or equivalent actuation component. Thereafter, thefluid infusion device can be prepared for the delivery of the medicationfluid as needed.

In accordance with an alternative method of operation, the fluidcartridge module 104 is installed after the housing 106 is affixed tothe body. In accordance with this option, the action of installing thefluid cartridge module 104 into the housing 106 engages or moves amechanical, electrical, magnetic, or other type of interface, which inturn releases a preloaded spring or equivalent actuation component toinsert the fluid delivery cannula into the body. Once the spring isreleased upon the first cartridge insertion, the fluid infusion device100 is put into a different state such that subsequent installations ofa fluid cartridge module will not trigger the insertion mechanism again.

In certain embodiments, the fluid infusion device 100 is realized as asingle-piece disposable component that is designed for continuous useover a designated period of time, such as three days. Although notalways required, the fluid infusion device 100 can be designed toaccommodate prefilled fluid cartridge modules 104, which may be providedby third party manufacturers in “off the shelf” volumes (e.g., 1.0 mL,1.5 mL, 2.0 mL, or 3.0 mL of medication fluid). It should be appreciatedthat the fluid infusion device 100 can also be suitably configured anddesigned to accommodate user-filled fluid cartridge modules 104.Referring to FIG. 2, each removable fluid cartridge module 104 can berealized as a single-use disposable reservoir that is not designed orintended to be refilled. The illustrated embodiment of the fluidreservoir cartridge module 104 includes a glass or plastic reservoir 116that is held in a carrier 118 or housing to facilitate insertion andremoval of the reservoir 116.

As mentioned above, the housing 106 of the fluid infusion device 100receives the removable fluid cartridge module 104 containing the desiredmedication fluid. The housing 106 also serves to contain the variety ofcomponents and elements that cooperate to support the functionality ofthe fluid infusion device 100. These internal components and elementscan include, without limitation: a printed circuit board; a vibrationmotor or other haptic feedback element; a battery or other energysource; a fluid pump mechanism; a drive motor coupled to actuate thefluid pump mechanism (or other devices, components, or means to actuatethe fluid pump mechanism, such as a solenoid, a nickel-titanium memorywire, or the like); an insertion mechanism for actuating atranscutaneous conduit assembly; sensors that interact with the drivemotor, the fluid pump mechanism, and/or the button 112; an outlet fluidconduit; and an inlet conduit assembly. Of course, an embodiment of thefluid infusion device 100 may include additional features, components,devices, and elements that are not depicted in the figures or describedin detail here.

The printed circuit board includes various electronic components,devices, and connections that cooperate to support the functions of thefluid infusion device 100. These components are enclosed within thehousing 106 for protection, water resistance, and the like. The printedcircuit board 130 may include or cooperate with any of the following,without limitation: switches; adjustment or trim elements such as apotentiometer; a processor device; memory; or the like. The vibrationmotor can be used to generate confirmation or alert signals as needed.Alternatively or additionally, the fluid infusion device 100 can includean audio transducer, an indicator light, a display element, or othercomponents to provide feedback to the user. The battery can be a singleuse element that can be discarded with the fluid infusion device. Thebattery provides the required voltage and current to operate the fluidinfusion device 100.

FIG. 3 depicts an embodiment of the fluid pump mechanism 136, which isfluidly coupled to the removable fluid cartridge module 104 duringoperation of the fluid infusion device 100. The fluid pump mechanism 136can be realized as a rotationally actuated micro pump that delivers acalibrated amount of medication fluid with each delivery cycle. In thisregard, the fluid pump mechanism 136 includes a stator and a rotor; therotor is actuated in a controlled manner by a drive motor 138. Asdescribed in more detail below, the fluid pump mechanism 136 functionsby translating rotational movement of the rotor into axial displacementof the rotor relative to the stator. In turn, the translational movementresults in the opening and closing of a series of valves that areinternal to the fluid pump mechanism 136 for purposes of drawing in themedication fluid from the fluid cartridge module 104. A biasing force(e.g., a spring force) forces the rotor toward the stator, which expelsthe fluid through the outlet of the fluid pump mechanism 136. In certainembodiments, the fluid pump mechanism 136 leverages the pump technologyoffered by Sensile Medical, although other types of pump technologiescan also be utilized.

In accordance with certain embodiments, the biasing force that urges therotor into the stator is provided by a molded plastic part that servesas both the spring element and a coupling component (to mechanicallycouple the drive motor 138 to the rotor). This spring coupler 164 isshown in FIG. 3. The spring coupler 164 eliminates the need for aseparate coupling element, which reduces parts count, reduces productcost, and simplifies manufacturing and assembly of the fluid infusiondevice 100. The spring coupler 164 can be a physically distinctcomponent that is mechanically attached between the drive motor 138 andthe rotor of the fluid pump mechanism 136. In alternative embodiments,the spring coupler 164 can be integrally fabricated with the rotor.

The drive motor 138 can be a direct current (DC) motor, a brushless DCmotor, a stepper motor, or the like. It should be appreciated that otherdrive methodologies could be used instead of the drive motor 138, suchas a nickel titanium memory wire and a ratcheting mechanism to createrotational motion to drive the fluid pump mechanism 136.

Thus, a full rotation of the rotor results in the delivery of a knownamount of medication fluid. After the fluid flow path of the fluidinfusion device 100 has been primed, each rotation of the rotor draws ameasured volume of medication fluid from the fluid cartridge module 104and expels the same amount of medication fluid from the cannula situatedin the patient.

With continued reference to FIG. 3, an inlet conduit assembly 144includes structure that is compatible with the removable fluid cartridgemodule 104. For example, the inlet conduit assembly 144 includes a fluidconduit 150 that terminates at a hollow reservoir needle (hidden fromview because it extends into the fluid cartridge module 104). The hollowreservoir needle enters the reservoir of the fluid cartridge module 104(via a septum) when the fluid cartridge module 104 is installed in thefluid infusion device 100. The fluid infusion device 100 also includes asealing element 154, which may be coupled to the inlet conduit assembly144 (alternatively, the sealing element 154 can be an integral part ofthe inlet conduit assembly 144). The sealing element 154 can be acompressible and resilient component that creates a fluid seal for theinlet conduit assembly 144 when the fluid cartridge module 104 isremoved from the housing 106 of the fluid infusion device 100. Morespecifically, the sealing element 154 is compressed when the fluidcartridge module 104 is installed, thus exposing the hollow reservoirneedle. The sealing element 154 extends to cover the end of the hollowreservoir needle when the fluid cartridge module 104 is removed, whichinhibits the ingress of contaminants, fluid, and air into the inletconduit assembly 144, and which inhibits leakage of medication fluidfrom the fluid flow path of the fluid infusion device 100.

Moreover, the inlet conduit assembly 144 is in fluid communication witha fluid inlet 156 of the fluid pump mechanism 136. The fluid inlet 156accommodates and receives an end of the fluid conduit 150, as shown inFIG. 3. This arrangement allows the fluid pump mechanism 136 to draw themedication fluid in from the fluid cartridge module 104, via the inletconduit assembly 144. The fluid pump mechanism 136 expels the medicationfluid from a fluid outlet 158, which is in fluid communication with theoutlet fluid conduit 142. FIG. 3 depicts only a portion of the outletfluid conduit 142. In certain embodiments, the outlet fluid conduit 142may be realized as part of a transcutaneous conduit assembly of thefluid infusion device 100, wherein the transcutaneous conduit assemblyalso includes a subcutaneous conduit (e.g., a soft cannula) that isinserted and positioned within the body of the patient.

The transcutaneous conduit assembly is in fluid communication with thefluid outlet 158 of the fluid pump mechanism 136. More specifically, inaccordance with the illustrated embodiment, the outlet fluid conduit 142is implemented as a flexible hollow needle having its proximal endfluidly coupled to the fluid outlet 158. The distal end of the flexiblehollow needle is sharp to accommodate the insertion of the subcutaneousconduit into the body of the patient during an insertion operation. Thedistal end of the flexible hollow needle is not shown in FIG. 3. Theproximal end of the subcutaneous conduit is fluidly coupled to theflexible hollow needle such that at least a portion of the needle isinitially inside the subcutaneous conduit (i.e., the subcutaneousconduit is carried by the flexible hollow needle before and during aninsertion operation). Accordingly, the subcutaneous conduit is in fluidcommunication with the fluid pump mechanism 136 such that the medicationfluid can be delivered to the body of the patient via the outlet fluidconduit 142 and the subcutaneous conduit.

The fluid infusion device 100 includes a flow path that accommodates thedelivery of the medication fluid from the fluid cartridge module 104 toa subcutaneous site in the body of the patient. A first fluid flow pathis at least partially defined by the inlet conduit assembly 144, whichresides between the fluid cartridge module 104 and the fluid pumpmechanism 136. The first fluid flow path may be considered to be theinlet flow path of the fluid pump mechanism 136. A second flow path(which may be considered to be the outlet flow path of the fluid pumpmechanism 136) is defined by the outlet fluid conduit 142 and thesubcutaneous conduit. In this regard, the second flow path terminates atthe distal end of the subcutaneous conduit. The overall flow path of thefluid infusion device 100, therefore, includes the first fluid flowpath, the fluid pump mechanism 136, and the second fluid flow path. Itshould be appreciated that the fluid flow path through the fluidinfusion device 100 can be established using any number of rigid needles(bent or straight), soft tubing, flexible steel tubing, or the like. Theparticular embodiment described herein is merely one possiblearrangement.

FIG. 4 is a block diagram that depicts an exemplary embodiment of asystem architecture 400 suitable for use with the fluid infusion device100. FIG. 4 depicts the housing 106 of the fluid infusion device 100,along with various components, elements, and devices that are housed by,enclosed within, or attached to the housing 106. In FIG. 4, solid arrowsrepresent electrical signal paths, dashed arrows represent mechanicalinteraction or cooperation between elements, and doubled arrowsrepresent fluid flow paths. It should be appreciated that an embodimentof the system architecture 400 can include additional elements,components, and features that may provide conventional functionalitythat need not be described herein. Moreover, an embodiment of the systemarchitecture 400 can include alternative elements, components, andfeatures if so desired, as long as the intended and describedfunctionality remains in place.

The illustrated embodiment of the system architecture 400 generallyincludes, without limitation: a printed circuit board 401; the removablefluid cartridge module 104; the fluid pump mechanism 136; the drivemotor 138; a fluid flow path 402; a fluid flow path 404; a cartridgesensor 406; one or more status sensors 408; one or more alerting devices410; an insertion mechanism 412; and a subcutaneous conduit 413. FIG. 4includes a number of items that were previously described, and thoseitems will not be redundantly described in detail here.

The printed circuit board 401 may include or carry at least some of theelectronics of the fluid infusion device 100, e.g., any number ofdiscrete or integrated devices, components, electrical conductors orconnectors, and the like. For example, the following items may be foundon the printed circuit board 401, without limitation: a battery 414; aprocessor device 420; a basal rate adjustment component 422; and aswitch 423. The printed circuit board 401 (or the items carried by theprinted circuit board 401) can be electrically coupled to other elementsof the system architecture 400 as needed to support the operation of thefluid infusion device 100. For example, the printed circuit board 401can be electrically coupled to at least the following, withoutlimitation: the fluid cartridge module 104; the fluid pump mechanism136; the drive motor 138; the cartridge sensor 406; the status sensors408; and the alerting devices 410. It should be appreciated thatelectrical connections to the printed circuit board 401 can be direct orindirect if so desired. Moreover, one or more components on the printedcircuit board 401 may support wireless data communication in someembodiments.

The flow path 402 fluidly couples the fluid cartridge module 104 to theinlet of the fluid pump mechanism 136, and the flow path 404 fluidlycouples the outlet of the fluid pump mechanism 136 to the subcutaneousconduit 413. The subcutaneous conduit 413 is fluidly coupled to the bodyof the patient. The drive motor 138 is electrically and mechanicallycoupled to the fluid pump mechanism 136 to control the operation of thefluid pump mechanism 136. Thus, the drive motor 138 can be turned on andoff as needed by the processor device 420 to control the position of therotor of the fluid pump mechanism 136.

The status sensors 408 can be electrically coupled to the fluid pumpmechanism 136 and to the printed circuit board 401 to monitor certainoperating conditions, parameters, or characteristics of the fluid pumpmechanism 136 and/or other components of the fluid infusion device 100.For example, the information provided by the status sensors 408 can beprocessed or otherwise utilized to determine the revolution count of thefluid pump mechanism 136, to determine the resting position of the fluidpump mechanism 136, to detect a downstream occlusion in the fluiddelivery path, to detect when the reservoir of the fluid cartridgemodule 104 is empty, or the like.

The alerting devices 410 can be electrically coupled to the printedcircuit board 401 for purposes of controlled activation. In this regard,activation of the alerting devices 410 can be controlled by theprocessor device 420 as needed. In certain embodiments, usermanipulation of the button 112 results in actuation of the switch 423,which in turn disables alerts or alarms generated by the alertingdevices 410.

The dashed arrow labeled “Cartridge Trigger Option” in FIG. 4 representsmechanical interaction (and/or electrical, magnetic, inductive, optical,capacitive, or other detection methodology) between the fluid cartridgemodule 104 and the insertion mechanism 412. In this regard, installationof the fluid cartridge module 104 into the housing 106 can be detectedto trigger the insertion mechanism 412. If the subcutaneous conduit 413is not yet inserted in the body of the patient (i.e., the springmechanism has not been actuated), then the insertion mechanism 412 firesto position the subcutaneous conduit 413 into a subcutaneous location.In alternative embodiments, a devoted insertion button 416 is used tofire the insertion mechanism 412. Accordingly, the dashed arrow labeled“Button Trigger Option” in FIG. 4 represents mechanical interaction(and/or some other detection methodology) between the insertion button416 and the insertion mechanism 412. In accordance with this option, theinsertion mechanism 412 is triggered by physical manipulation of theinsertion button 416, and the subcutaneous conduit 413 is installed(unless the insertion mechanism 412 has already been fired).

The processor device 420 can be realized in any form factor. In certainembodiments, the processor device 420 is realized as an applicationspecific integrated circuit (ASIC) that is mounted to the printedcircuit board 401. The ASIC can also include a suitable amount of memorythat is needed to support the operations and functions of the fluidinfusion device. In this regard, techniques, methods, and processes maybe described herein in terms of functional and/or logical blockcomponents, and with reference to symbolic representations ofoperations, processing tasks, and functions that may be performed byvarious computing components or devices. Such operations, tasks, andfunctions are sometimes referred to as being computer-executed,computerized, software-implemented, or computer-implemented. It shouldbe appreciated that the various block components shown in the figuresmay be realized by any number of hardware, software, and/or firmwarecomponents configured to perform the specified functions. For example,an embodiment of a system or a component may employ various integratedcircuit components, e.g., memory elements, digital signal processingelements, logic elements, look-up tables, or the like, which may carryout a variety of functions under the control of one or moremicroprocessors or other control devices.

When implemented in software or firmware, various elements of thesystems described herein are essentially the code segments orcomputer-readable instructions that perform the various tasks. Incertain embodiments, the program or code segments are stored in atangible processor-readable medium, which may include any medium thatcan store or transfer information. Examples of a non-transitory andprocessor-readable medium include an electronic circuit, a semiconductormemory device, a ROM, a flash memory, an erasable ROM (EROM), a floppydiskette, a CD-ROM, an optical disk, a hard disk, or the like. Thesoftware that performs the described functionality may reside andexecute at, for example, an ASIC.

More specifically, the processor device 420 may be implemented orperformed with a general purpose processor, a content addressablememory, a digital signal processor, an application specific integratedcircuit, a field programmable gate array, any suitable programmablelogic device, discrete gate or transistor logic, discrete hardwarecomponents, or any combination designed to perform the functionsdescribed here. In particular, the processor device 420 may be realizedas a microprocessor, a controller, a microcontroller, or a statemachine. Moreover, the processor device 420 may be implemented as acombination of computing devices, e.g., a combination of a digitalsignal processor and a microprocessor, a plurality of microprocessors,one or more microprocessors in conjunction with a digital signalprocessor core, or any other such configuration.

The processor device 420 includes or cooperates with memory, which canbe realized as RAM memory, flash memory, EPROM memory, EEPROM memory,registers, or any other form of storage medium known in the art. Thememory can be implemented such that the processor device 420 can readinformation from, and write information to, the memory. In thealternative, the memory may be integral to the processor device 420. Asan example, the processor device 420 and the memory may reside in asuitably designed ASIC.

In the context of the particular embodiments described in more detailbelow, the processor device 420 can implement, cooperate with, orotherwise support the operation of a detection circuit (and applicableprocessing logic) that functions to detect downstream occlusions in afluid flow path, upstream occlusions in a fluid flow path, end ofreservoir conditions in a fluid infusion device, and/or other detectableoperating conditions. To this end, the processor device 420 can executesuitably written computer instructions that cause the processor device420 to perform the various detection tasks, operations, and method stepsdescribed below in the context of the different detection methodologies.

The simple user interface can include a physical button 112, acapacitive button, a thin film force sensitive resistor as a button(using deformation of a specific part of the housing 106 as a button),etc. The button 112 can be activated to deliver a bolus, to remove thedevice from an inactive shelf mode, to provide a self-check, to respondto alerts or alarms, and the like. The system architecture 400 mayinclude an optional insertion button 416 that can be activated torelease the conduit insertion mechanism 412.

One implementation is to have a single software-set basal rate and bolusbutton value. For example, one SKU can be used for a fluid infusiondevice having a basal setting of 2 Units/hr, wherein each press of thebutton 112 results in the delivery of two Units of bolus therapy. Adifferent SKU can be used for a fluid infusion device having a basalsetting of 1 U/hr, wherein each press of the button 112 results in thedelivery of one Unit of bolus therapy. In practice, the bolus value canbe set based on research of total insulin consumption so as to simplifythe operation of the device. For example, if a patient uses 100 U/day ofbasal therapy, they likely need more bolus therapy and, therefore, a 5.0Unit bolus deliver for each button press might be suitable. On the otherhand, if a patient uses 20 U/day of basal therapy, they likely need lessbolus therapy and, therefore, the bolus button for the device might beconfigured to deliver only 1.0 Unit per button press.

Regarding the bolus delivery function, each time the patient presses thebutton 112, the fluid infusion device 100 delivers the programmed bolusvalue and waits for the next button press. Thus, if the fluid infusiondevice 100 has a preset bolus value of 5.0 Units and the patient needs15.0 Units, then the patient presses the button 112 one time to deliverthe first 5.0 Units, presses the button 112 a second time to deliver thenext 5.0 Units, and presses the button 112 a third and final time forthe last 5.0 Units.

The fluid infusion device 100 also allows for multiple button presses,provides confirmation (vibration, auditory, indicator lights), and thendelivers the entire amount. For example, the fluid infusion device 100may process three back-to-back button presses, recognize a total ofthree presses, provide user feedback, wait for confirmation, and thendeliver a total of 15.0 Units.

Patient-specific programming can be achieved through a physicianprogrammer via a wired or wireless communication session. For example,an infrared window can be provided in the housing of the fluid infusiondevice to accommodate wireless adjustments or programming. Other methodsto adjust the basal rate utilize a dial, a knob, or other adjustmentcomponent that the physician or patient can manipulate. The adjustmentcomponent can be connected to the printed circuit board 401 and,specifically, to the processor device 420 for purposes of changing thetiming and/or other characteristics of the fluid pump mechanism 136.FIG. 4 depicts a basal rate adjustment component 422 that is intended torepresent the various methodologies and components that serve to adjustthe programmed basal rate of the fluid infusion device 100. One simpleand low cost way to visualize and confirm the adjustment involves theuse of a clear window on the housing of the fluid infusion device and acolored dial with markings corresponding to the adjustment setting.

The system architecture 400 may include or cooperate with anycombination of alerting devices 410, including, without limitation: avibration motor; a piezoelectric audio transducer; one or more indicatorlights (e.g., light emitting diodes or other lamp components); a speakerprotected by a hydrophobic membrane; and the like.

The drive motor 138 can be electrically coupled to the printed circuitboard 401 with a connector and wires, plated traces on the housing 106,or the like. The drive motor 138 can be coupled to the fluid pumpmechanism 136 using a coupler and a spring (not shown). Alternatively,certain embodiments can utilize the one-piece spring coupler 164described above with reference to FIG. 3.

The status sensors 408 can be used to monitor the health and operationof the fluid pump mechanism 136. For example, the status sensors 408 canbe used to check the winding resistance of the drive motor 138. Thesystem architecture 400 can also be configured to detect certain faultconditions such as fluid path occlusion, an end of reservoir condition,the Units remaining in the reservoir, and the like. The status sensors408 can be utilized to check for these and other operating conditions ifso desired.

In some embodiments, occlusion can be detected by using a Hall sensor todetermine the axial position rate of change of the rotor of the fluidpump mechanism 136. The sensor system can include a magnet positioned onthe rotor, and a Hall sensor on the printed circuit board 401. Pumpingair rather than fluid, versus not pumping due to an occlusion, willprovide a different linear rate of change of the rotor and, therefore,can be correlated to the pumping condition. This methodology willrequire knowledge of the rotational state of the rotor, i.e., when therotor has completed one full turn. This can be achieved with a magneticencoder, an optical encoder, a physical feature on the pump rotor thatcontacts a switch every time a rotation is complete, or the like. Theswitch can be a physical, inductive, capacitive, photo-interrupt, orother type of switch. Multiple optical encoders can be used in place ofa Hall sensor, one to detect angular position of the rotor, and one todetect linear position. Similarly, magnetic or other encoders can beused.

An end of reservoir condition can be detected using the same methodologydescribed above for occlusion detection, or it can be detected using anoptical sensor to monitor the position of the plunger or piston of thefluid cartridge module 104. Other techniques and technologies can alsobe utilized to determine when the fluid cartridge module 104 needs to bereplaced. Various techniques and methodologies for detecting downstreamocclusions and upstream occlusions (e.g., “end of reservoir” conditions)are described in a more fulsome manner below.

The amount of medication fluid remaining can be determined using anoptical sensor that detects the location of the plunger near the end ofthe reservoir volume. A countdown value can be calculated to provide anestimate of the number of Units remaining in the reservoir.Alternatively, the amount of fluid remaining can be determinedmagnetically by providing a magnet on the plunger of the reservoir. Amagnetic sensor in the housing 106 can be used to detect the magnet. Asyet another option, inductive or capacitive detection methodologies canbe leveraged to determine the amount of medication fluid remaining inthe fluid cartridge module 104. The detected position is calibrated tocorrespond to a specific volume of fluid remaining in the reservoir.

Prefilled fluid cartridge modules 104 can be provided in a housing thatfacilitates insertion into the housing 106 and removal from the housing106, as described above. The fluid cartridge modules 104 can be designedto provide a convenient and easy to handle form factor. In certainembodiments, installation of the fluid cartridge module 104 activatesthe cannula insertion mechanism 412, which eliminates the need for anextra patient step and system component devoted to this function. InFIG. 4, the arrow labeled “Cartridge Trigger Option” represents thisfunctionality.

The fluid cartridge module 104 may also be configured to communicate tothe processor device 420 (or initiate such communication) whether or notit has been installed. The arrow labeled “Reservoir In/Out” in FIG. 4represents this communication. Thus, the act of inserting the fluidcartridge module 104 into the housing 106 can be electronically detectedto take appropriate action. Conversely, if the fluid cartridge module104 is removed, the fluid infusion device 100 can suspend basal andbolus therapy. When the fluid cartridge module 104 is reinstalled, thetherapy can be resumed. The manner in which the fluid cartridge module104 is detected may vary from one embodiment to another. In certainembodiments, a physical feature on the fluid cartridge module 104interacts with a feature or a mechanical component of the fluid infusiondevice 100 that, in turn, triggers a switch on the printed circuit board401. Alternatively (or additionally), installation of the fluidcartridge module 104 can be achieved by creating a short circuit acrosselectrical contacts when the fluid cartridge module 104 is installed.For example, a metal cap on the fluid cartridge module 104 can serve asthe electrical conductor that creates the short circuit. Alternatively,the exterior of the fluid cartridge module 104 can include printedplating or a conductive trace on specific locations that create a shortacross contacts of the fluid infusion device 100 when the fluidcartridge module 104 is installed. As yet another example, installationof the fluid cartridge module 104 can be detected by physical contact,capacitive sensing, inductive sensing, optical sensing, acousticsensing, magnetic sensing, infrared sensing, RFID technology, or thelike. The cartridge sensor 406 depicted in FIG. 18 is intended torepresent these and other possible methodologies, components, andfeatures that detect when the fluid cartridge module 104 isseated/installed, and when the fluid cartridge module 104 isunseated/uninstalled.

Fluid Pump Mechanism

FIGS. 5-8 are diagrams that depict a fluid pump mechanism 500 in variousstages during one pump cycle. FIGS. 5-8 schematically depict the fluidpump mechanism 500 in a simplified way for ease of understanding. Anembodiment of the fluid pump mechanism 500 can be configured as neededto suit the requirements of the particular application. The fluid pumpmechanism 500 generally includes, without limitation: a rotor 502; astator 504; and a biasing element 506. The rotor 502 includes an axialextension section 508 that is at least partially received within thestator 504. For this example, the rotor 502 is driven such that itrotates relative to the stator 504. In alternative implementations, thestator 504 could be rotated relative to the rotor 502, or both the rotor502 and the stator 504 could be rotated relative to each other. Thebiasing element 506 (which may be realized as a spring, such as thespring coupler 164 shown in FIG. 3) provides a biasing force that urgesthe rotor 502 toward the stator 504.

The fluid pump mechanism 500 includes a fluid inlet 510 and a fluidoutlet 512. Although not always required, the fluid inlet 510 is locatedat the end of the stator 504, and the fluid outlet 512 is located on theside of the stator 504 (which is consistent with the embodiment shown inFIG. 3). The fluid inlet 510 can be in communication with the reservoirof the fluid cartridge module 104, and the fluid outlet 512 can be incommunication with the fluid flow path that leads to the body of thepatient. Alternative arrangements for the fluid inlet 510 and the fluidoutlet 512 are also contemplated by this disclosure. Internal fluidpathways, sealing structures, and valve structures are not depicted inFIGS. 5-8 for the sake of clarity and simplicity.

FIGS. 5-8 depict different states of the fluid pump mechanism 500 duringone fluid delivery cycle, which corresponds to one revolution of therotor 502. FIG. 5 shows the fluid pump mechanism 500 in an initial statewhere the internal valve and sealing structures effectively seal thefluid inlet 510 and the fluid outlet 512. In this initial state, therotor 502 is fully seated within the stator 504, and the axialdisplacement of the rotor 502 relative to the stator 504 is consideredto be zero. FIG. 6 shows the fluid pump mechanism 500 in a fluid intakestate. In this state, the fluid inlet 510 is free to draw the medicationfluid into the fluid pump mechanism 500, but the fluid outlet 512remains sealed. Fluid is drawn into the fluid inlet 510 as the axialdisplacement of the rotor 502 relative to the stator 504 increases.Continued rotation of the rotor 502 eventually causes the fluid pumpmechanism 500 to reach the state shown in FIG. 7. In this state, thefluid inlet 510 and the fluid outlet 512 are sealed, and the fluid isready to be expelled from the fluid pump mechanism 500. Moreover, theaxial displacement of the rotor 502 relative to the stator 504 ismaximized while in the state shown in FIG. 7. Further rotation of therotor 502 enables the biasing element 506 to force the rotor 502 backinto the stator 504, which in turn expels the fluid from the fluidoutlet 512. In the state depicted in FIG. 8, the fluid outlet 512 isfree to expel the fluid from the fluid pump mechanism 500, but the fluidinlet 510 remains sealed to inhibit backflow. The biasing element 506urges the rotor 502 into its fully seated position, and further rotationof the rotor 502 eventually returns the fluid pump mechanism 500 to theinitial state shown in FIG. 5. Under normal and expected operatingconditions, one complete rotation of the rotor 502 corresponds to onepumping cycle (i.e., one fluid delivery cycle) having a defined fluidintake period and a defined fluid expulsion period. During one pumpingcycle, medication fluid is drawn from the fluid cartridge module 104and, thereafter, medication fluid is expelled from the fluid outlet 512for delivery to the patient.

FIG. 9 is an exploded perspective view of an exemplary embodiment of afluid pump mechanism 600 having a rotor 602 and a stator 604. The fluidpump mechanism 600 operates in the same manner summarized above withreference to FIGS. 5-8. An embodiment of the fluid pump mechanism 136,500, 600 can be designed and configured in accordance with the pumpdescribed in United States Patent Application Publication number US2009/0123309 (the content of which is incorporated by reference herein).For clarity and ease of understanding, the following description onlyrefers to the fluid pump mechanism 600.

As mentioned above with reference to FIGS. 5-8, the rotor 602 has anaxial extension section 608 that is shaped and sized for insertion intoa rotor chamber 610 of the stator 604. The axial extension section 608protrudes from the endcap 609 of the rotor 602, and at least a portionof the axial extension section 608 fits inside the rotor chamber 610.The axial extension section 608 can rotate and move in the axialdirection relative to the stator 604. The fluid pump mechanism 600includes a first valve and a second valve (not shown in FIG. 9) thatopen and close as a function of the angular and axial position of therotor 602 relative to the stator 604. The valves are realized using asuitably configured sealing structure and/or sealing elements thatcooperate with fluid supply channels formed in the axial extensionsection 608. The sealing structure and/or sealing elements arepositioned inside the stator 604.

Rotation of the rotor 602 also results in axial displacement of therotor 602 relative to the stator 604. The rotation-based axialdisplacement is provided by cooperating cam elements located on therotor 602 and the stator 604. FIG. 9 depicts a portion of the stator camelement 612; the rotor cam element, however, is hidden from view in FIG.9. When the rotor 602 rotates relative to the stator 604, the angularand axial movement of the axial extension section 608 results in theopening and closing of the two valves. During a complete rotationalcycle of the fluid pump mechanism 600, the axial displacement of therotor 602 relative to the stator 604 generates a pumping action insidethe rotor chamber 610 (as described above with reference to FIGS. 5-8).In this regard, the rotor chamber 610 defined in the stator 604 mayinclude or serve as the fluid chamber of the fluid pump mechanism 600.

FIG. 10 is a perspective view of an exemplary embodiment of a stator 704of a fluid pump mechanism, and FIG. 11 is a perspective view of anexemplary embodiment of a compatible rotor 702. It should be appreciatedthat the fluid infusion device that hosts the rotor 702 and the stator704 will include appropriate structure, components, features, and/orelements that support and hold the rotor 702 and the stator 704 in thedesired positions, and that accommodate axial and rotational movement ofthe rotor 702 relative to the stator 704. For the sake of clarity andsimplicity, such cooperating structure, components, features, and/orelements are not depicted in FIG. 10 or FIG. 11.

Although the stator 704 has a different configuration than the stator604 depicted in FIG. 9, the operating concepts and functionality areidentical for purposes of this description. In this regard, the stator704 includes a stator cam element 706 and a rotor opening 708 (asdescribed above). The rotor 702 generally includes, without limitation:an endcap 712; a proximal axial extension 714; a distal axial extension716; a first fluid supply channel 718 formed in the proximal axialextension 714; a second fluid supply channel 720 formed in the distalaxial extension 716; and a rotor cam element 722.

The fluid supply channels 718, 720 are realized as thin slits thatextend from the outer surfaces of the axial extensions 714, 716. Sealingelements located inside the stator 704 cooperate with the fluid supplychannels 718, 720 to act as valves that open and close as a function ofthe angular and axial position of the rotor 702 relative to the stator704. This enables pumping of medication fluid supplied from the fluidcartridge module 104 (see FIG. 3 and FIG. 4) due to a changes in volumein the rotor opening 708 caused by the axial displacement of the rotor702.

The endcap 712 can be suitably configured to mate with or otherwisecooperate with the drive motor 138, such that the angular position ofthe rotor 702 can be controlled as needed. Moreover, the endcap 712 canbe suitably configured to mate with or otherwise cooperate with abiasing component that urges the rotor 702 toward the stator 704. Forexample, the endcap 712 can be coupled to or integrally fabricated withthe spring coupler 164 shown in FIG. 3.

The axial displacement of the rotor 702 relative to the stator 704 isdefined by the cooperating cam elements 706, 722. The cam elementscontact each other during each pumping cycle to adjust the axialposition of the rotor 702 as a function of the angular position of therotor 702 relative to the stator 704. For the illustrated embodiment(see FIG. 11), the rotor cam element 722 is positioned on the interiorportion of the endcap 712, and it extends over a certain predefined arc.The rotor cam element 722 resembles a ramp having a variable heightrising from a reference surface of the rotor 702. More specifically, therotor cam element 722 increases in height over the predefined arc. Incontrast, the stator cam element 706 can be realized as a simpleprotrusion having a stator cam surface that is designed to “ride” alongand up the ramp of the rotor cam element 722. It should be appreciatedthat the stator cam element 706 need not be realized as a simpleprotrusion, and that an embodiment of the fluid pump mechanism canreverse the functions of the cam elements (such that the rotor camelement 722 is realized as a simple protrusion and the stator camelement 706 is realized as a ramp).

FIGS. 12-14 are diagrams that depict the cooperation between the statorcam element 706 and the rotor cam element 722. FIGS. 12-14 only show thestator cam element 706; the remaining portion of the stator 704 isomitted from these figures. The wide arrow 730 in FIGS. 12-14 representsthe axial biasing force that is applied to the rotor 702. This axialbiasing force is intended to urge the rotor cam element 722 toward thestator cam element 706 and toward the reference surface of the rotor.The arrow 732 in FIGS. 12-14 indicates the direction of travel of therotor cam element 722 relative to the stator cam element 706. Asexplained above, the rotor cam element 722 moves (relative to the statorcam element 706) in response to the rotation of the rotor 702.

FIG. 12 depicts a state where the stator cam element 706 resides on therotor cam element 722. More specifically, the stator cam element 706 ispositioned on the sloped portion of the rotor cam element 722. As thestator cam element 706 continues to “ride” along the rotor cam element722, the rotor 702 becomes displaced relative to the stator 704. Themaximum displacement occurs at the highest section (the plateau) of therotor cam element 722. The illustrated embodiment of the rotor camelement 722 ends abruptly, as best shown in FIG. 13, which depicts thevertical “shelf” defined at the end of the rotor cam element 722. FIG.13 depicts a state where the stator cam element 706 has cleared therotor cam element 722, and before the rotor 702 has been pushed backtoward the stator 704 by the biasing force. In this regard, FIG. 13shows the gap distance between the stator cam element 706 and areference surface 736 of the endcap 712. This gap distance correspondsto the maximum axial displacement between the stator 704 and the rotor702. FIG. 14 depicts a state that immediately follows the state shown inFIG. 13. The biasing force moves the rotor 702 toward the stator 704such that the stator cam element 706 contacts the reference surface 736.The state shown in FIG. 14 corresponds to the minimum axial displacementbetween the stator 704 and the rotor 702.

FIG. 15 is a graph that includes a plot of rotor axial position versusrotor angular position, for normal and typical operating conditions. Thevertical axis indicates the axial position (displacement) of the rotor702 relative to the stator 704, and the horizontal axis indicates theangular position of the rotor 702. One pumping cycle corresponds to 360degrees of rotation, and FIG. 15 depicts a plot that spans two pumpingcycles. FIG. 15 includes regions superimposed over the plot; the regionsrepresent periods during which the valves are open. More specifically,the region 802 corresponds to a first period during which thesecond/outlet valve (V2) is open, the region 804 corresponds to a secondperiod during which the first/inlet valve (V1) is open, the region 806corresponds to a third period during which V2 is open, the region 808corresponds to a fourth period during which V1 is open, and the region810 corresponds to a fifth period during which V2 is open. The gapsbetween these five regions correspond to periods during which bothvalves are closed.

The first section 814 of the plot (where the axial displacement isapproximately zero) corresponds to a period during which the stator camelement 706 is in contact with the reference surface 736. The secondsection 816 of the plot (where the axial displacement increases fromabout zero to about 0.95 mm) corresponds to a period of time duringwhich the stator cam element 706 rides onto the rotor cam element 722.Notably, the axial displacement increases until the stator cam element706 reaches the maximum height defined by the rotor cam element 722.During this time, the first valve is open, the second valve is closed,and the axial displacement of the rotor 702 increases the volume of thefluid chamber inside the stator 704, which in turn causes fluid to bedrawn into the fluid pump mechanism. Accordingly, the second section 816of the plot corresponds to a fluid intake period. The third section 818of the plot (where the axial displacement is constant at about 0.95 mm)corresponds to a period during which the stator cam element 706 rides onthe top of the plateau defined by the rotor cam element 722. During mostof this period, both of the valves are closed.

The fourth section 820 of the plot (where the axial displacementdecreases from about 0.95 mm to about zero) corresponds to a period oftime immediately after the stator cam element 706 travels beyond therotor cam element 722 (see FIG. 13 and FIG. 14). In other words, thestator cam element 706 “falls off” and disengages the plateau of therotor cam element 722, and the biasing force axially displaces the rotor702 toward the stator 704 such that the rotor cam element 722 movestoward the reference surface 736. Eventually, the stator cam element 706reaches and contacts the reference surface 736. During this time, thefirst valve is closed, the second valve is open, and the axialdisplacement of the rotor 702 causes the fluid to be expelled from thefluid pump mechanism via the second valve. Accordingly, the fourthsection 820 of the plot corresponds to a fluid expulsion period. Thefifth section 822 of the plot (where the axial displacement isapproximately zero) corresponds to another period during which thestator cam element 706 is in contact with the reference surface 736.Thus, after a fluid expulsion period and before the next fluid intakeperiod, the stator cam element 706 is in contact with the referencesurface 736. In this regard, the fifth section 822 is akin to the firstsection 814, and the next pumping cycle proceeds as the rotor 702continues to rotate.

Downstream Occlusion Detection

A downstream occlusion in the fluid delivery flow path occurs whensomething blocks or inhibits the flow of the fluid after it leaves thefluid pump mechanism. Downstream occlusion detection techniques aredesirable to increase the safety of a medication infusion device. Withparticular reference to the fluid pump mechanism described here,downstream occlusion detection can employ one or both of the followinggeneral methodologies: (1) axial position measurement of the rotor 702relative to the stator 704; and (2) force/pressure measurement of thefluid path.

As mentioned above, the axial position of the rotor 702 (relative to thestator 704) as a function of angular rotation is at the core of thepumping action of the fluid pump mechanism. FIG. 15 illustrates thenormally expected behavior of the fluid pump mechanism. In practice, theaxial position of the rotor 702 relative to the stator 704 can bemeasured/monitored for purposes of detecting delivery anomalies. Forexample, during normally expected operation, the stator cam element 706disengages from the rotor cam element 722 and the axial biasing element(usually a spring) causes the fluid to be expelled through the secondvalve (V2). In the presence of a downstream occlusion, however, outgoingfluid flow is restricted and incompressibility of the fluid restrictsthe contraction of the rotor position, thus impacting the axial positionof the rotor 702. In this regard, FIG. 16 is a graph that includes aplot 840 of rotor axial position versus rotor angular position for adownstream occlusion condition. FIG. 16 also shows the normally expectedplot 842 in dashed lines.

The plot 840 indicates how a downstream occlusion affects the axialdisplacement of the rotor 702. Here, the plot 840 closely tracks thetheoretical plot 842 during the fluid intake portion of the pumpingcycle. When the second valve opens and the stator cam element 706disengages from the rotor cam element 722, however, the axial biasingforce does not overcome the fluid pressure caused by the occlusion.Accordingly, the rotor 702 does not completely return to its startingpoint against the stator 704 until shortly after the first valve opens.When the first valve opens, the fluid can backflow into the fluidreservoir, which in turn enables the axial biasing force to return therotor 702 to its starting position. As shown in FIG. 16, the axialdisplacement of the rotor 702 hovers at or near 0.85 mm during theperiod when the second valve is open, but it quickly drops to about zeroonce the first valve opens. These characteristics of the plot 840 areindicative of a downstream occlusion. The following sections present anumber of techniques and methodologies that are designed to detect andrespond to a downstream occlusion, which might cause the behaviordepicted in FIG. 16.

Downstream Occlusion Detection: Methodology 1

The occlusion detection methodology presented here utilizes a sensorsystem integrated into the fluid pump mechanism. The basic design,configuration, and operation of the fluid pump mechanism are consistentwith that previously described. The sensor system includes a metal traceor similarly conductive sensor contact element that is installed on orintegrated into the rotor and in the area away from the rotor camelement (also referred to as the “off-ramp position”). The sensor systemalso includes a sensing element on or integrated into the stator,wherein the sensing element cooperates with the sensor contact elementduring operation of the fluid pump mechanism. In some embodiments, thesensing element is realized as two discrete traces or conductive leadsthat terminate in the area of the stator cam element. The sensor contactelement can be shaped, sized, and positioned such that the stator camelement only makes contact with the sensor contact element during normalfluid delivery operations (and such that the stator cam element does notmake contact with the sensor contact element when the downstream fluidpath is occluded).

The conductive traces on the stator can be interconnected toappropriately configured electronics, a detection circuit, a processor,or the like. Software running on the fluid infusion device can monitorthe state of the sensor system (open/close, high/low, etc.) to determinean operating condition, such as the state of fluid delivery. Duringnormal delivery cycles, the detection circuit observes one binarypattern produced by the sensor system (open, close, open, close, etc.)that correlates to the various intake and expulsion cycles. Duringcertain fault conditions, however, the detection circuit observes adifferent binary pattern (e.g., open, open), which in turn initiates analarm or an alert message.

FIG. 17 is an end view of an exemplary embodiment of a rotor 852 of afluid pump mechanism that implements the occlusion detection methodologydescribed here. FIG. 18 is an end view of an exemplary embodiment of astator 854 of a fluid pump mechanism that implements the occlusiondetection methodology, and FIG. 19 is a diagram that depicts the stator854 cooperating with a detection circuit 856. The fluid pump mechanismthat incorporates the rotor 852 and the stator 854 is similar to thatdescribed previously with reference to FIGS. 5-16.

FIG. 17 is an axial end view from the perspective of one looking intothe bottom of an endcap 858 of the rotor 852. FIG. 17 depicts thefollowing features, which were described in detail above: an axialextension section 860, which is positioned in the center of the endcap858; a reference surface 862; and a rotor cam element 864. As mentionedabove, the rotor cam element 864 rises above the reference surface 862from a lower edge 866 to an upper edge 868. FIG. 17 also depicts anexemplary embodiment of a sensor contact element 870, which resides on(or is integrated into) the reference surface 862. In practice, thethickness of the sensor contact element 870 is negligible for purposesof operating the fluid pump mechanism in the manner describedpreviously. The sensor contact element 870 is located in an area that isunoccupied by the rotor cam element 864. As shown in FIG. 17, the sensorcontact element 870 can be realized as an arc-shaped electricallyconductive trace that is sized such that the reference surface 862defines a first gap between the lower edge 866 of the rotor cam element864 and the sensor contact element 870, and a second gap between theupper edge 868 of the rotor cam element 864 and the sensor contactelement 870. The span of the sensor contact element 870 and thelocations of its leading and trailing edges are carefully selected forcompatibility with the angular timing of the rotor 852, and forcompatibility with the open/closed states of the inlet and outletvalves. In certain embodiments, the sensor contact element 870 isfabricated using a Laser Direct Structuring (LDS) process comprised of adoped organometallic material that is laser activated and then plated, atwo-shot with a chemical activation and then plated, an insert moldedcontact, etc.

FIG. 18 is an axial end view from the perspective of one looking intothe fluid chamber of the stator 854. FIG. 18 depicts a stator camelement 874, which is realized as a protruding tab, and a portion of asensing element that terminates at or near the stator cam surface 876.Although not always required, the illustrated embodiment of the sensingelement includes a first electrically conductive lead 878 (or trace)having an end that is exposed at the stator cam surface 876, and asecond electrically conductive lead 880 (or trace) having an end that isexposed at the stator cam surface 876. Each lead 878, 880 also has asecond end that cooperates with or is coupled to the detection circuit856 (see FIG. 19). In alternative embodiments, the sensing element couldbe realized using conductive springs, tabs, brushes, or the like.

The leads 878, 880 cooperate with the detection circuit 856 to detectwhether or not the stator cam surface 876 is in contact with the sensorcontact element 870. For example, the detection circuit 856 can monitorthe characteristics of a detection signal that is obtained from theleads 878, 880 in response to the changing angular position of the rotor852. The detection signal could be a measured voltage, current, or thelike, having two measurable states corresponding to a contact state anda non-contact state. In this regard, the detection signal obtained fromthe sensing element can be a binary signal having a first logical stateand a second logical state, where the first logical state corresponds tocontact between the stator cam element 874 and the sensor contactelement 870, and the second state corresponds to non-contact between thestator cam element 874 and the sensor contact element 870. Consequently,a first binary pattern of the detection signal obtained during onerotation of the rotor 852 is indicative of normal and expected operationof the fluid pump mechanism, while a second binary pattern of thedetection signal during one rotation of the rotor is indicative of afault condition of the fluid pump mechanism, e.g., a downstreamocclusion, a faulty biasing element, or the like. Under normal operatingconditions, the first binary pattern will alternate between the twological states (high, low, high, low, high, low . . . ). If thedownstream fluid path is occluded, however, the fluid back pressure willprevent the stator cam element 874 from reaching the sensor contactelement 870 and, therefore, the second binary pattern will include onlyone state (i.e., the non-contact state). The detection circuit caneasily distinguish between these two binary patterns to resolve whetherthe fluid infusion device is operating as usual or is operating underconditions that indicate a downstream occlusion.

The sensor contact element 870 is shaped, sized, and positioned suchthat, under normal and expected operating conditions, the stator camelement 874 is in contact with the sensor contact element 870immediately following each fluid expulsion period. The stator camelement 874 remains in contact with the sensor contact element 870 for adefined angular range of the rotor 852, but the sensor contact element870 ends before the angular position that corresponds to the next fluidintake period (i.e., the sensor contact element 870 ends before thelower edge 866 of the rotor cam element 864. Moreover, the sensorcontact element 870 is located in an area on the reference surface 862that corresponds to a valve state in which the inlet valve is closed andthe outlet valve is open (see FIG. 15 and FIG. 16). Depending on theparticular timing and configuration of the fluid pump mechanism, atleast a portion of the sensor contact element 870 can be located in anarea on the reference surface 862 that corresponds to a valve state inwhich both the inlet valve and the outlet valve are closed.

Under downstream occlusion conditions, however, fluid pressure caused byan occlusion downstream of the fluid pump mechanism prevents the statorcam element 874 from contacting the sensor contact element 870 after thefluid expulsion period. This enables the detection circuit to determinethe presence of a downstream occlusion in response to thecharacteristics of the detection signal obtained under the downstreamocclusion conditions. If the detection circuit detects a downstreamocclusion in this manner, it can initiate an alert, an alarm, a warningmessage, or the like. In some embodiments, the detection circuittriggers an alert in response to detecting a binary pattern in thedetection signal that corresponds to a fault condition. In otherembodiments, an alert is triggered after a particular binary pattern isdetected during a plurality of consecutive rotations of the rotor 852.This requirement may be implemented to minimize false alarms.

In alternative embodiments, the sensor contact element is insteadlocated on the rim 882 of the endcap 858 (see FIG. 17). In suchembodiments, the angular span of the sensor contact element can beidentical or functionally equivalent to that shown in FIG. 17 for thesensor contact element 870. Locating the sensor contact element on therim 882 instead of inside the endcap 858 may be desirable for ease ofmanufacturing, reliability, and robust performance. If the sensorcontact element is positioned on the rim 882, then the electricallyconductive leads of the stator 854 will also be relocated forcompatibility with the alternative positioning of the sensor contactelement. For example, the leads can be located on a rim or other surface884 of the stator 854. This type of arrangement is also shown in FIGS.44-46 in the context of another embodiment.

Downstream Occlusion Detection: Methodology 2

FIG. 20 is a schematic block diagram that illustrates an exemplaryembodiment of an occlusion detection system suitable for use with afluid infusion device having a fluid cartridge module 900, a fluid pumpmechanism 902, and a fluid conduit 904 between the fluid cartridgemodule 900 and the fluid pump mechanism 902. The fluid pump mechanism902 is designed to draw medication fluid from the fluid cartridge module900 during an intake cycle, and thereafter expel the medication fluidduring an expulsion cycle. In this regard, the basic operation andfunctionality of the fluid cartridge module 900 and the fluid pumpmechanism 902 are similar to that described above with reference toFIGS. 1-4.

The embodiment of the occlusion detection system shown in FIG. 20includes an electroactive polymer (EAP) sensor 906 and a detectioncircuit 908 that is operatively coupled to the EAP sensor 906. The EAPsensor 906 can be realized as a ring-shaped or cylindrical-shapedcomponent that is secured around the fluid conduit 904. For thisparticular embodiment, the fluid conduit 904 is somewhat resilient, suchthat it can expand and contract in response to changes in fluidpressure. The EAP sensor 906 is positioned around the exterior of thefluid conduit 904 for purposes of detecting expansion and contraction ofthe fluid conduit 904 as a function of the operating state of the fluidpump mechanism 902. More specifically, the EAP sensor 906 can monitorthe condition of the fluid conduit 904 during fluid intake cycles, fluidexpulsion cycles, dwell times, etc.

EAP materials are generally known. For this particular application, theEAP sensor 906 is fabricated from a material (such as a thin film) thatgenerates energy, electricity, voltage, current, or a measurablequantity as a function of mechanical stress or strain imparted thereto.The response of the EAP sensor 906 can be detected and analyzed by thedetection circuit 908 as needed. Thus, the EAP sensor 906 is suitablyconfigured to detect or measure the expansion and contraction of thefluid conduit 904 in an ongoing manner.

During a normal and expected fluid delivery cycle, the resilient fluidconduit 904 will collapse or contract during the fluid intake cycle,while the fluid pump mechanism 902 is drawing fluid from the fluidcartridge module 900. Thereafter, the fluid conduit 904 will recover andregain its “nominal” shape (during the fluid expulsion cycle).Accordingly, the EAP sensor 906 is designed to respond to thischaracteristic contraction and recovery, and the detection circuit 908takes appropriate action (if any) when the normally expected signal fromthe EAP sensor 906 is produced. In contrast, if the fluid flow pathdownstream of the fluid pump mechanism 902 is occluded, then the fluidconduit 904 will not collapse or contract to the same extent that itdoes during normal delivery. More specifically, the fluid conduit 904will remain pressurized in the presence of a downstream occlusion untilthe inlet valve opens again for the next intake stroke. Opening of theinlet valve allows the pressurized fluid to backflow into the upstreamfluid path, which in turn allows the resilient fluid conduit 904 toshrink or collapse (relative to its pressurized state). In thisscenario, the detection circuit 908 can analyze the output of the EAPsensor 906, determine that a downstream occlusion has occurred, and takeappropriate action such as generating an alert.

It should be appreciated that the output of the EAP sensor 906 can alsobe monitored to detect an “end of reservoir” condition. In this regard,when the fluid cartridge module 900 is empty, the stopper of the fluidreservoir no longer moves because it has reached the limit of itstravel. Thus, the fluid pump mechanism 902 generates a negative pressureon the inlet side, which collapses the fluid conduit 904 to a greaterextent than experienced during normal delivery (and the fluid conduit904 does not recover back to its nominal shape).

FIG. 20 shows the EAP sensor 906 monitoring an upstream fluid conduitthat resides between the fluid cartridge module 900 and the fluid pumpmechanism 902. This arrangement can be effective at detecting upstreamocclusions (e.g., an end of reservoir condition). Alternatively oradditionally, the system can employ a similar EAP sensor to monitorexpansion and contraction of a downstream fluid conduit that is locateddownstream of the fluid pump mechanism 902. Monitoring a downstreamfluid conduit can be effective for purposes of detecting downstreamocclusions.

Downstream Occlusion Detection: Methodology 3

In accordance with another downstream occlusion detection methodology,an electrical switch is incorporated in the downstream fluid flow path.For example, a section of the fluid conduit that resides downstream ofthe fluid pump mechanism can be fabricated from an elastomeric materialthat is electrically conductive, or that includes an electricallyconductive element affixed thereto. The electrically conductive elementrepresents one terminal of a mechanical switch; the other terminal canbe positioned in a suitable location adjacent to the fluid conduit.

During a normal and expected fluid delivery cycle, the elastomericmaterial will expand slightly during the fluid expulsion stage. In thepresence of a downstream occlusion, however, the fluid pump mechanism isable to generate substantially more fluid pressure. The increasedpressure causes the elastomeric material to expand. As the fluid pumpmechanism continues to operate and increase the fluid pressure, theconductive element of the fluid conduit contacts the other switchterminal and creates an electrical short. The closing of the mechanicalswitch can be detected by a suitably designed detection circuit as anindicator of the downstream occlusion.

Downstream Occlusion Detection: Methodology 4

FIG. 21 is a simplified diagram of an exemplary embodiment of an opticalor acoustic based occlusion detection system suitable for use with afluid infusion device having a fluid cartridge module, a fluid pumpmechanism, and a fluid conduit 904 (as generally described above withreference to FIG. 20). FIG. 21 has been simplified to only show therelevant section of the fluid conduit 904. In lieu of (or in additionto) the EAP sensor 906 described above, the embodiment of the occlusiondetection system presented here utilizes a non-contact sensingmethodology. In certain embodiments, the majority of the fluid conduit904 is fabricated from a rigid and stiff material 920, such as stainlesssteel, that exhibits little to no deformation with changes in fluidpressure. At least one section of the fluid conduit 904, however,includes a resilient and compliant component 922. The component 922moves (expands and contracts) in response to pressure changes inside thefluid conduit 904.

The embodiment of the occlusion detection system shown in FIG. 21includes a detection circuit 924 that suitably configured tointerrogate, observe, or otherwise detect the status of the component922 without physically touching the component 922. The detection circuit924 can utilize one or more of the following sensing technologies,without limitation: optical; acoustical; imaging; ultrasound; infrared;or magnetic. The detection circuit 924 can include an interrogationsignal emitter 926 that generates interrogation signals 928 (acoustic,optical, magnetic, etc.) for purposes of determining the state of thecomponent 922. In this way, the detection circuit 924 can monitor thecondition of the component 922 during fluid intake cycles, fluidexpulsion cycles, dwell times, etc.

During a normal and expected fluid delivery cycle, the resilientcomponent 922 will collapse or contract during the fluid intake cycleand will quickly recover and regain its “nominal” shape (during thefluid expulsion cycle). FIG. 21 shows the contracted state of thecomponent 922 using a solid line, and the nominal state of the component922 using a dashed line. In contrast, if the fluid flow path downstreamof the fluid pump mechanism is occluded, then the component 922 will notcollapse or contract. The detection circuit 924 employs one or moreappropriate non-contact sensing technologies to determine the state ofthe component 922 and, in turn, to determine whether a downstreamocclusion has occurred. It should be appreciated that the flexiblecomponent 922 can also be monitored to detect an “end of reservoir”condition. In this regard, when the fluid cartridge module is empty, thecomponent 922 will collapse but will not return back to its nominalshape.

Downstream Occlusion Detection: Methodology 5

As described in detail above with reference to FIGS. 5-14, a rotaryfluid pump mechanism includes a rotor and a stator that cooperate todraw fluid from a fluid reservoir and deliver the fluid to an outletconduit. Axial displacement of the rotor relative to the stator is afunction of the angular position of the rotor. Simply put, the rotormoves back and forth relative to the stator during normal and expectedfluid pumping cycles. The occlusion detection methodology presented inthis section employs at least one non-contact sensing scheme to monitorthe position of the rotor relative to the stator during operation of thefluid pump mechanism.

FIG. 22 is a simplified diagram of an exemplary embodiment of anocclusion detection system that utilizes position sensing techniques.FIG. 22 depicts a rotor 940 and a stator 942 of a rotary fluid pumpmechanism of the type previously described. Rotation of the rotor 940usually results in axial displacement of the rotor 940 relative to thestator 942. This axial displacement is represented by the arrow 944 inFIG. 22. As explained previously, the axial position of the rotor 940(as a function of angular position of the rotor 940) is repeatable andpredictable during normal fluid delivery conditions (see FIG. 15). Incontrast, the axial position of the rotor 940 exhibits substantiallydifferent characteristics in the presence of a downstream occlusion, dueto the back pressure caused by the occlusion (see FIG. 16). Thetechniques presented here detect the relative position of the rotorand/or the stator during operation of the fluid infusion device, and thedetected position information is used to determine whether or not thedownstream fluid path is occluded.

The embodiment of the occlusion detection system shown in FIG. 22includes a detection circuit 946 that cooperates with one or morenon-contact sensors associated with the rotor 940 and/or the stator 942.For the sake of generality and completeness, FIG. 22 shows multiplerotor sensors 948 and multiple stator sensors 950, each of whichcooperates with the detection circuit 946 to provide respective sensorsignals, measurable quantities, data, or information that can beanalyzed and processed as needed for purposes of occlusion detection.Depending on the particular embodiment, the occlusion detection systemcan utilize any one of the sensors 948, 950 or any suitable combinationof two or more sensors 948, 950.

In accordance with some embodiments, an accelerometer is used for atleast one of the rotor sensors 948. The accelerometer data can beprocessed by the detection circuit to calculate the axial displacementvelocity or acceleration of the rotor 940 as a function of its angularposition. In this regard, the axial velocity/acceleration of the rotor940 can be characterized for normal and expected fluid delivery cyclesand for downstream occlusion conditions. Referring again to FIG. 15 andFIG. 16, the axial velocity/acceleration of the rotor 940 is expected tobe relatively high during a normal fluid delivery period, and relativelylow when the downstream fluid path is occluded. The detection circuit946 can be designed and programmed in an appropriate manner to respondto changes in the axial velocity/acceleration of the rotor 940 thatmight be indicative of a downstream occlusion.

In accordance with certain embodiments, the occlusion detection systememploys a light source and a light sensor to monitor the axial positionof the rotor 940 relative to the sensor. In this regard, one or more ofthe sensors 948, 950 can be realized as a light sensor. Alternatively,one or more light sensors external to the rotor 940 and external to thestator 942 can be used. In accordance with alternative embodiments, alight sensor is provided on the stator 942 (or the rotor 940), and areflective element is provided on the rotor 940 (or the stator 942).

In yet other embodiments, the sensors 948, 950 are selected to supportthe desired non-contact sensing technology. In this regard, any of thefollowing non-contact sensing techniques can be utilized with theocclusion detection system depicted in FIG. 22, without limitation:magnetic sensing using, for example, a Hall sensor arrangement;inductive sensing that relies on inductive coupling between the stator942 and the rotor 940; capacitive sensing that relies on capacitivecoupling between the stator 942 and the rotor 940; infrared sensing; oroptical imaging.

In accordance with some embodiments, the occlusion detection systemincludes a force or pressure sensor 954 that is suitably configured andarranged to measure the biasing force associated with the rotor 940. Asmentioned previously with reference to FIGS. 5-8, a biasing element canbe employed to urge the rotor 940 toward the stator 942. The sensor 954measures the force 956, which can vary during a fluid delivery cycle.Thus, the force 956 can be characterized for normal and expected fluiddelivery cycles and for downstream occlusion conditions, and thedetection circuit 946 can be designed and programmed in an appropriatemanner to respond to changes in the detected force profile that might beindicative of a downstream occlusion.

Downstream Occlusion Detection: Methodology 6

The occlusion detection methodology presented in this section utilizes apotentiometer as a sensing element to determine the axial position ofthe rotor of the fluid pump mechanism. In this regard, FIG. 23 is asimplified perspective view of an exemplary embodiment of a rotor 960having an electrical contact 962 attached thereto, and FIG. 24 is asimplified diagram of an exemplary embodiment of an occlusion detectionsystem that cooperates with the rotor 960. The occlusion detectionsystem also includes a variable resistance element 964 that cooperateswith the electrical contact 962 to form a potentiometer. The electricalcontact 962 and the variable resistance element 964 can be electricallycoupled to a detection circuit 966, which supports the occlusiondetection methodology described here. In practice, the variableresistance element 964 can be realized as a component of the detectioncircuit 966. Moreover, the variable resistance element 964 can beintegrated with or coupled to the stator of the fluid pump mechanism ifso desired.

The electrical contact 962 can be realized as a conductive tab, brush,or protrusion that extends from an exterior surface 968 of the rotor960. The electrical contact 962 is shaped, sized, and positioned on theexterior surface 968 such that it makes electrical contact with thevariable resistance element 964 once per revolution of the rotor 960. Incertain embodiments, the electrical contact 962 is grounded such that itcooperates with the variable resistance element 964 to form a voltagedivider. Although not depicted in FIG. 23 or FIG. 24, the electricalcontact 962 can be electrically coupled to ground potential usingconductive traces, a ground spring, a wire, or the like.

FIG. 24 depicts the rotor 960 at the sensor interrogation time, i.e.,when the electrical contact 962 is touching the variable resistanceelement 964. The angular position of the rotor 960 (at the time theelectrical contact 962 is electrically coupled to the variableresistance element 964) corresponds to a desired interrogation orsampling point of the fluid delivery cycle. For example, the electricalcontact 962 can be placed such that it contacts the variable resistanceelement 964 immediately following each expected fluid expulsion period(see FIG. 15). The specific timing can be determined based on the knownangular position characteristics of the fluid pump mechanism.

As explained previously with reference to FIGS. 5-14, the rotor 960 isaxially displaced as a function of its angular position. The arrow 970in FIG. 24 represents the axial displacement of the rotor 960. Axialdisplacement of the rotor 960 causes the electrical contact 962 to shiftback and forth, because the electrical contact 962 is fixed relative tothe rotor 960. During normal and expected fluid delivery cycles, theelectrical contact 962 should make contact with the variable resistanceelement 964 within a predictable and repeatable range of possiblelocations. Consequently, the resistance of the potentiometer changes,and a measured quantity (e.g., voltage) as detected by the detectioncircuit 966 will be within a certain range during normal deliverycycles. In contrast, the electrical contact 962 will touch the variableresistance element 964 at a considerably different location when thedownstream fluid flow path is occluded. Accordingly, the resistance ofthe potentiometer and the measured voltage will be outside of the normalrange of values when the output flow path is occluded. The detectioncircuit 966 can be designed and programmed in an appropriate manner torespond to changes in the resistance of the potentiometer that might beindicative of a downstream occlusion.

FIG. 24 depicts an embodiment where the electrical contact 962 resideson the rotor 960 and the variable resistance element 964 is external tothe rotor 960. In other embodiments, the variable resistance element 964resides on the rotor 960 and the electrical contact 962 is external tothe rotor 960. Regardless of which configuration is used, the operatingprinciple remains the same.

Downstream Occlusion Detection: Methodology 7

The occlusion detection methodology presented in this section utilizesan electrical contact as a digital switch to indicate the presence of adownstream occlusion. In this regard, FIG. 25 is a simplified diagram ofan exemplary embodiment of an occlusion detection system that utilizesan electrical contact 976 that is integrated with or affixed to therotor 978 (similar to that described in the previous section withreference to FIG. 23 and FIG. 24). The occlusion detection system shownin FIG. 25 includes an electrically conductive element 980 that isexternal to the rotor 978. The electrically conductive element 980 ispositioned and arranged such that the electrical contact 976 touches theconductive element 980 at a specified angular position of the rotor 978,e.g., the angular position that corresponds to a period immediatelyfollowing the fluid expulsion cycle of the fluid pump mechanism.

FIG. 25 depicts the normal and expected state following the fluidexpulsion cycle. The electrical contact 976 is expected to make contactwith the conductive element 980. In contrast, if the downstream flowpath is occluded, then the electrical contact 976 will be displaced fromthe conductive element 980. The detection circuit 982 can distinguishbetween a closed electrical contact (which indicates normal deliverystatus) and an open electrical contact (which indicates an occludedstatus). In practice, therefore, the electrical contact 976 can begrounded or otherwise held at an appropriate reference voltage. In someembodiments, a second electrically conductive element 984 can beutilized to detect an occluded state, wherein the conductive element 984is positioned to be aligned with the electrical contact 976 when therotor 978 is in the shifted position caused by an occlusion.

Downstream Occlusion Detection: Methodology 8

The occlusion detection methodology presented in this section utilizesan electrical contact having a variable resistance that indicates thepresence of a downstream occlusion. In this regard, FIG. 26 is asimplified end view of a stator 990 having an electrically conductiverim 992, and FIG. 27 is a simplified diagram of an exemplary embodimentof an occlusion detection system that cooperates with the stator 990.FIG. 27 also depicts a rotor 994 that cooperates with the stator 990.The rotor 994, the stator 990, and the associated fluid pump mechanismfunction in the manner generally described above with reference to FIGS.5-16. For the sake of simplicity and clarity, the various electricalconnections and detection circuit are not shown in FIG. 27.

The illustrated embodiment of the stator 990 terminates at theconductive rim 992, which faces the rotor 994 (see FIG. 27). Theconductive rim 992 is electrically coupled to the detection circuit. Therotor 994 includes an electrically conductive contact 996, which may berealized as a conductive brush, tab, spring, or the like. The conductivecontact 996 is also electrically coupled to the detection circuit. Theconductive contact 996 maintains physical and electrical contact withthe conductive rim 992 during operation of the fluid pump mechanism,regardless of whether the downstream fluid flow path is occluded. Inthis regard, as the rotor 994 spins relative to the stator 990, theconductive contact 996 follows the circular path of the conductive rim992.

The conductive contact 996 is designed such that the resistance of theconductive contact 996 varies as a function of its physical compressionand/or deflection. The conductive contact 996 compresses or deflectsmore as the gap between the rotor 994 and the conductive rim 992 closes.Conversely, the conductive element expands or returns to its nominalshape as the gap increases. Thus, the resistance of the conductivecontact 996 changes as a function of the axial displacement of the rotor994 relative to the stator 990. The resistance between the conductivecontact 996 and the conductive rim 992 can be measured by the detectioncircuit, which can be suitably designed and programmed to respond tochanges in the measured resistance that might be indicative of adownstream occlusion. For example, under normal and expected operatingconditions, the detection circuit expects to obtain a resistancemeasurement that falls within a particular range when the angularposition of the rotor corresponds to the period immediately followingthe fluid expulsion cycle. If a downstream occlusion prevents the rotor994 from moving toward the stator 990, then the measured resistance willbe different by at least a threshold amount. The detection circuit canrespond in an appropriate manner to such detected changes in themeasured resistance.

The arrangement depicted in FIG. 26 and FIG. 27 can also be configuredfor use as a simple on/off switching mechanism. In this context, thedetection circuit can be designed to detect whether or not theconductive contact 996 is electrically coupled to the conductive rim992. For this alternative implementation, the conductive contact 996 andthe conductive rim 992 are configured such that an electrical connectionis made only when the stator cam element resides on the referencesurface. The detection circuit can detect the presence of a downstreamocclusion in a manner similar to that described above with reference toFIGS. 17-19.

Downstream Occlusion Detection: Methodology 9

The occlusion detection methodology presented in this section utilizes aforce sensor that generates output levels that can be analyzed todetermine whether the downstream fluid path is occluded. In this regard,FIG. 28 is a simplified diagram of an exemplary embodiment of anocclusion detection system that utilizes one or more force sensors incooperation with the fluid pump mechanism. FIG. 28 depicts a stator1002, a rotor 1004, and a biasing element 1006 of a fluid pump mechanismthat functions in the manner generally described above with reference toFIGS. 5-16. FIG. 28 also shows a force sensor 1008 positioned betweenthe rotor 1004 and the stator 1002, and another force sensor 1010positioned such that it can measure the biasing force of the biasingelement 1006. One or both of the force sensors 1008, 1010 can beutilized in an embodiment of the fluid infusion device. The forcesensors 1008, 1010 are suitably designed and configured to generateoutput levels in response to force imparted thereto, and the outputlevels can be obtained, processed, and analyzed by an appropriatedetection circuit 1012.

For the illustrated embodiment, the force sensor 1008 is positioned andconfigured to measure force applied by the stator 1002 to the forcesensor 1008. Thus, the force sensor 1008 can be located on a flange,shoulder, or other structural feature of the rotor 1004 such that thestator 1002 (or a physical feature thereof) can interact with the forcesensor 1008 when necessary to obtain force measurements. In alternativeembodiments, the force sensor 1008 can be positioned and configured tomeasure force applied by the rotor 1004 to the force sensor 1008. Inthis regard, the force sensor 1008 can be located on a flange, shoulder,or other structural feature of the stator 1002 such that the rotor 1004(or a physical feature thereof) can interact with the force sensor 1008when necessary to obtain force measurements.

The force sensor 1010 can be positioned and configured to measure theforce applied by the biasing element 1006 to the rotor 1004, the forceapplied by the rotor 1004 to the biasing element 1006, etc. FIG. 28depicts the force sensor 1010 coupled between one end of the biasingelement 1006 and a supporting structure 1014 of the fluid infusiondevice. In alternative implementations, the force sensor 1010 can becoupled between the other end of the biasing element 1006 and the rotor1004. It should be appreciated that other arrangements and locations fora force sensor can be utilized in an embodiment, and that theconfiguration shown in FIG. 28 is not intended to be restrictive orlimiting.

The force sensor 1008, 1010 is designed to react in response to forceimparted thereto. In this regard, electrical, mechanical, magnetic,and/or other measurable or detectable characteristics of the forcesensor 1008, 1010 vary in accordance with the amount of force applied tothe force sensor 1008, 1010. In practice, the force sensor 1008, 1010might implement or otherwise leverage known sensor technologies. Asshown in FIG. 28, the force sensor 1008, 1010 includes at least oneelectrical lead that is electrically coupled to the detection circuit1012 of the fluid infusion device. Alternatively, the force sensor 1008,1010 could use wireless data communication technology to provideforce-related data to the detection circuit 1012. In certainimplementations, the force sensor 1008, 1010 is suitably configured toindicate or generate a plurality of different output levels that can bemonitored and/or determined by the detection circuit 1012. In practice,the output levels obtained from the force sensor 1008, 1010 areinitially conveyed as analog voltages or analog currents, and thedetection circuit 1012 includes an analog-to-digital converter thattransforms a sampled analog voltage into a digital representation.Conversion of sensor voltage into the digital domain is desirable forease of processing, comparison to threshold values, and the like.

In particular embodiments, the force sensor 1008, 1010 is realized as anelectromechanical component having at least one variable resistance thatchanges as the force applied to the force sensor 1008, 1010 changes. Inalternative embodiments, the force sensor 1008, 1010 is a capacitivesensor, a piezoresistive sensor, a piezoelectric sensor, a magneticsensor, an optical sensor, a potentiometer, a micro-machined sensor, alinear transducer, an encoder, a strain gauge, or the like, and thedetectable parameter or characteristic might be compression, shear,tension, displacement, distance, rotation, torque, force, pressure, orthe like. In practice, changing characteristics of the force sensor1008, 1010 are associated with output signal characteristics that areresponsive to a physical parameter to be measured. Moreover, the rangeand resolution of the monitored output signal provides for the desirednumber of output levels (e.g., different states, values, quantities,signals, magnitudes, frequencies, steps, or the like) across the rangeof measurement. For example, the force sensor 1008, 1010 might generatea low or zero value when the applied force is relatively low, a high ormaximum value when the applied force is relatively high, andintermediate values when the applied force is within the detectablerange.

In certain exemplary embodiments, the detection circuit 1012 of thefluid infusion device maintains a constant supply voltage across theforce sensor 1008, 1010, and the monitored output signal of the forcesensor 1008, 1010 is a signal current that passes through a resistivematerial of the force sensor 1008, 1010. Thus, the signal current varieswith the amount of force applied to the force sensor 1008, 1010 becausethe resistance of the force sensor 1008, 1010 varies with force and thesupply voltage across the force sensor 1008, 1010 is constant. Thedetection circuit 1012 converts the monitored signal current into asignal voltage, which is then used as an indication of the forceimparted to the force sensor 1008, 1010 (which varies as a function ofaxial displacement of the rotor 1004 relative to the stator 1002). Inalternative embodiments, a constant supply current is used and thesignal voltage across the force sensor 1008, 1010 varies with force.

As explained above with reference to FIGS. 5-16, the axial displacementof the rotor 1004 (relative to the stator 1002) exhibits a predictableback and forth pattern that corresponds to each pumping cycle of thefluid pump mechanism. For the force-based methodology presented in thissection, the force sensor 1008, 1010 generates output levels in responseto force imparted thereto, and the force sensor 1008, 1010 cooperateswith the detection circuit 1012 for purposes of occlusion detection. Tothis end, the detection circuit 1012 obtains and processes the sensoroutput levels to detect occlusions in the fluid path downstream of thefluid pump mechanism. In accordance with the exemplary methodologydescribed here, the force sensor 1008, 1010 is used to obtain forcemeasurements following each fluid expulsion period and before the nextfluid intake period. Moreover, the force measurements are obtained whenthe outlet valve is open. (see FIG. 15 and FIG. 16).

Under normal and expected operating conditions, the axial displacementof the rotor 1004 should be zero or very close to zero during the forcemeasurement period because the biasing element 1006 should force therotor 1004 into the stator 1002 to expel fluid from the outlet valve.Consequently, the force sensor 1008, 1010 generates baseline or nominaloutput levels that fall within a range of expected output levels. If theforce sensor 1008 is utilized, then the nominal output levels willtranslate to a relatively high force measurement. Conversely, if theforce sensor 1010 is utilized, then the nominal output levels willtranslate to a relatively low force measurement.

Under downstream occlusion conditions, however, fluid pressure canprevent or inhibit axial displacement of the rotor 1004 toward thestator 1002 (see FIG. 16). As a result, the force sensor 1008, 1010generates outlier output levels that fall outside the range of expectedoutput levels. The outlier output levels are indicative of a downstreamocclusion. More specifically, the detection circuit 1012 can detect anddetermine the presence of a downstream occlusion in response toobtaining the outlier output levels. For example, if the detectioncircuit 1012 observes outlier output levels that satisfy certainthreshold criteria (e.g., above or below a predetermined threshold valuefor any one pumping cycle or for a specified number of consecutivepumping cycles), then the detection circuit 1012 can declare that adownstream occlusion has occurred and, thereafter, take appropriateaction.

If the force sensor 1008 is deployed, then a downstream occlusion willresult in output levels that translate to relatively low forcemeasurements that can be detected and distinguished from normal andexpected force measurements (which will be higher). Conversely, if theforce sensor 1010 is used, then a downstream occlusion will result inoutput levels that translate to relatively high force measurements thatcan be detected and distinguished from normal and expected forcemeasurements (which will be lower). Regardless of which force sensor1008, 1010 is employed, the detection circuit 1012 can respond in anappropriate manner when it detects a downstream occlusion based onoutlier force sensor readings.

Downstream Occlusion Detection: Methodology 10

The occlusion detection methodology presented in this section assumesthat the fluid pump mechanism described above (with reference to FIGS.5-16) uses a conductive compression spring as the biasing element 506.The conductive spring is electrically coupled to a detection circuitthat is suitably configured to measure the inductance of the conductivespring. In practice, the detection circuit can include aninductance-to-digital converter to obtain readings that are indicativeof the inductance of the conductive spring.

The inductance of the conductive spring is a function of itscompression/extension. Accordingly, the measured inductance of theconductive spring should vary as a function of the axial displacement ofthe rotor relative to the stator. Thus, the measured inductance can beanalyzed at certain times during the pumping cycle for purposes ofdetermining whether or not a downstream occlusion has occurred. Forexample, the inductance of the conductive spring can be checked at thetime immediately following each fluid expulsion cycle, when the rotorcam element is expected to be in contact with the reference surface (seeFIG. 15 and FIG. 16). Measured inductance values that fall within arange of expected values are indicative of normal operating conditions.In contrast, measured inductance values that fall outside the range ofexpected values may be indicative of a downstream occlusion.

Downstream Occlusion Detection: Methodology 11

The occlusion detection methodology presented in this section utilizesoptical detection techniques to determine whether the downstream fluidpath is occluded. In accordance with one implementation, an opticalsensor or detector interrogates an optically detectable pattern (such asa dot array) that is printed on an exposed surface of the rotor of thefluid pump mechanism. In accordance with an alternative implementation,an optical sensor or detector interrogates a physical structure of therotor.

FIG. 29 is a simplified diagram of an exemplary embodiment of anocclusion detection system that utilizes optical sensing technology.FIG. 29 depicts a stator 1022 and a rotor 1024 of a fluid pump mechanismthat functions in the manner generally described above with reference toFIGS. 5-16. The rotor 1024 includes at least one optically detectablefeature that can be monitored during the operation of the fluid pumpmechanism. In this regard, FIG. 28 also shows an exemplary embodiment ofan optically detectable feature, which is realized as an opticallydetectable pattern 1026 located on an exposed surface 1028 of the rotor1024. For the illustrated embodiment, the optically detectable pattern1026 is a dot array, which can be printed, affixed to, or integratedinto the exposed surface 1028. Other types of optically detectablepatterns 1026 can be employed if so desired.

The optically detectable pattern 1026 can be located around the outercircumference of the endcap of the rotor 1024, as depicted in FIG. 29.In certain embodiments, the optically detectable pattern 1026 is visibleregardless of the angular position of the rotor 1024. In otherembodiments, the optically detectable pattern 1026 need not completelyencircle the exposed surface 1028. In such embodiments, the opticallydetectable pattern 1026 can be located in one or more regions of therotor 1024, where the regions correspond to angular positions of therotor 1024 that require optical sensing.

The fluid infusion device includes a detection circuit 1030 thatincludes an optical emitter/sensor element 1032, along with theappropriate optical sensing processing logic and intelligence. Thedetection circuit 1030 can leverage any known or available opticalsensing or detection technology, and such conventional technology willnot be described in detail here. For example, the detection circuit 1030can employ LED or laser sensing technology that is commonly used inoptical mouse peripherals. In this regard, an optical mouse contains asmall LED that interrogates a work surface, and a CMOS sensor thatdetects the reflected light. The sensor sends the captured image data toa signal processor for analysis to determine how the images/patternshave changed over time. In practice, the detection circuit 1030 mayinclude a suitably configured emitter that generates opticalinterrogation signals, and a compatible sensor that can detect thepattern 1026 in response to the interrogation signals. In this way, thedetection circuit 1030 can resolve any or all of the following, at anygiven time: the angular position of the rotor 1024; the axialposition/displacement of the rotor 1024; the angular velocity of therotor 1024; the angular acceleration of the rotor 1024; the velocity ofthe rotor 1024 in the axial direction; and the acceleration of the rotor1024 in the axial direction.

Notably, the optically detectable pattern 1026 is fixed relative to theexposed surface 1028 and, therefore, the optically detectable pattern1026 rotates and axially translates as a function of the angularposition of the rotor 1024. As described in detail above with referenceto FIGS. 5-16, one rotation of the rotor 1024 corresponds to one pumpingcycle, and the rotor 1024 (along with the pattern 1026) axiallytranslates back and forth during normal and expected operatingconditions. Accordingly, the optical emitter/sensor element 1032includes an optical sensing range that covers the desired portion of theoptically detectable pattern 1026, and that contemplates the range ofaxial displacement of the rotor 1024. This allows the detection circuit1030 to optically interrogate the pattern 1026 during operation of thefluid pump mechanism and, in response to the optical detection,determine the operating condition or state of the fluid pump mechanism.

As explained above with reference to FIGS. 5-16, the rotor 1024 axiallytranslates in a predictable back-and-forth manner when the fluidinfusion device is operating under normal and expected conditions. Inturn, the optically detectable pattern 1026 axially translates in thesame predictable manner. The detection circuit 1030 is configured toobserve this characteristic movement of the pattern 1026, which isindicative of normal operating conditions. In this regard, the detectioncircuit 1030 can determine that the operating condition of the fluidpump mechanism is normal. The pattern 1036 can also be observed todetect rotation of the rotor 1024 for purposes of correlating theangular position of the rotor 1024 with its axial displacement (if sodesired).

Under downstream occlusion conditions, the rotor 1024 does not return toits nominal axial position. In other words, the fluid pressure caused bya downstream occlusion prevents the rotor cam element from contactingthe reference surface as expected. Consequently, during each occludedpumping cycle, the optically detectable pattern 1026 axially translatesin accordance with a different characteristic movement that is opticallydistinguishable from the normally expected characteristic movement.Thus, the detection circuit 1030 can observe the differentcharacteristic movement to determine that the operating condition of thefluid pump mechanism corresponds to a downstream occlusion.

In accordance with alternative embodiments, the optically detectablefeature of the rotor is realized as a physical structure (or structures)that can be observed by the detection circuit. In this regard, FIG. 30is a simplified perspective view of an exemplary embodiment of a rotor1040 having physical features that cooperate with an optical detectioncircuit (not shown), and FIG. 31 is a side view of a section of therotor 1040.

FIG. 30 depicts the portion of the rotor 1040 that remains exposedduring operation of the fluid pump mechanism, including an endcap 1042and a tapered section 1044 having an asymmetrical profile (see FIG. 31).The tapered section 1044 represents one physical structure of the rotor1040 that can be optically interrogated by a detection circuit such asthe detection circuit 1030 described previously. The tapered section1044 can be realized as an integrated portion of the rotor 1040, or itcould be a separate component that is attached to the shaft of the rotor1040. It should be appreciated that the optically detectable physicalstructure can be shaped, sized, and configured in an alternate way, andthat the generally conical tapered section 1044 shown in FIG. 30 andFIG. 31 is merely one example of a suitable implementation.

The optical interrogation signal can be focused at a specified locationsuch that different areas of the tapered section 1044 are observed asthe rotor 1040 is displaced in the axial direction. For example, anarrower section 1046 of the tapered section 1044 can be observed whenthe rotor 1040 returns to its nominal baseline position (immediatelyfollowing fluid expulsion), and a wider section 1048 of the taperedsection 1044 can be observed when the rotor 1040 is axially displacedduring a fluid intake cycle.

The detection circuit can be designed to detect the different widths ofthe tapered section 1044 and to determine whether or not the downstreamfluid path is occluded, based on the detected width and the angularposition of the rotor 1040. Alternatively, the detection circuit can bedesigned to detect the distance between the exposed surface of thetapered section 1044 and the optical emitter, and to determine whetheror not the downstream fluid path is occluded, based on the detecteddistance and the angular position of the rotor 1040.

The rotor 1040 can also include another optically detectable physicalfeature, such as a tab 1050 located around the periphery of the endcap1042. The detection circuit can include a second optical emitter/sensorto interrogate the periphery of the endcap 1042 for purposes ofdetecting the rotation of the rotor 1040. In this regard, the tab 1050is optically detected once per revolution of the rotor 1040. Notably,the tab 1050 can be located in a particular position on the rotor 1040in accordance with the desired timing characteristics of the detectioncircuit, the expected axial translation characteristics, and theconfiguration of the tapered section 1044 such that the detectioncircuit can effectively determine whether or not a downstream occlusionhas occurred during rotation of the rotor 1040.

Upstream Occlusion Detection (End of Reservoir Detection)

As mentioned previously with reference to FIGS. 1-4, the fluid infusiondevice cooperates with a fluid cartridge module 104 having a fluidreservoir. The fluid reservoir has a fluid-tight plunger, piston, orstopper that is pulled up by the negative pressure created by the fluidpump mechanism during each fluid intake cycle. The negative pressuredraws the medication fluid out of the fluid reservoir, through the inletconduit, and into the fluid pump mechanism. If the piston gets stuck inthe fluid reservoir, then the fluid pump mechanism will not be able todraw any fluid from the reservoir. This fault condition is known as anupstream occlusion because the fluid flow path leading into the fluidpump mechanism is effectively blocked. Similarly, if the fluid reservoiris empty, then the fluid pump mechanism will be pulling on a vacuumrather than drawing in fluid. This condition can also be considered anupstream occlusion because the patient will not be receiving theexpected amount of medication fluid when the reservoir is empty.

The following sections relate to various techniques and technologies fordetecting an empty fluid reservoir (also referred to as an upstreamocclusion). These techniques are desirable to increase the safety of amedication infusion device. With particular reference to the fluid pumpmechanism described here, end of reservoir detection can employ one ormore of the following general methodologies, without limitation: (1)detecting that the stopper has reached an end position; (2) detectingthat the fluid pump mechanism is pulling on a vacuum rather than drawingin fluid; (3) measurement of the stopper position over the length of thereservoir; and (4) observing axial displacement characteristics of therotor relative to the stator.

Upstream Occlusion Detection: Methodology 1

The upstream occlusion detection methodology presented in this sectionrelies on a sensor that detects when the stopper of the fluid reservoirit at or near its end position. In this regard, FIG. 32 is a simplifieddiagram of an exemplary embodiment of an end of reservoir detectionsystem interrogating a fluid reservoir 1060 at a time when medicationfluid 1062 remains in the fluid reservoir 1060, and FIG. 33 is asimplified diagram of the system at a time when the fluid reservoir 1060is empty. The fluid reservoir 1060 is coupled to a fluid pump mechanism1064 via a conduit 1065. The fluid pump mechanism 1064 can be designedand configured as described above with reference to FIGS. 5-16.

The fluid reservoir 1060 includes a barrel 1066 and a stopper 1068 thatcreates a fluid tight seal with the inner wall of the barrel 1066. Thestopper 1068 is shaped, sized, and configured to slide within the barrel1066 as the medication fluid 1062 is drawn out. As explained above, thefluid pump mechanism 1064 creates negative pressure during each fluidintake cycle, and the negative pressure causes the medication fluid 1062to enter the chamber of the fluid pump mechanism 1064. This action alsocauses the stopper 1068 to move (to the right in FIG. 32 and FIG. 33)within the barrel 1066.

The embodiment of the system shown in FIG. 32 and FIG. 33 includes adetection circuit 1070 that is suitably configured to interrogate,observe, or otherwise detect the position of the stopper 1068 as itapproaches and/or reaches its end position (shown in FIG. 33).Accordingly, in certain embodiments the barrel 1066 is clear ortranslucent to accommodate the operation of the detection circuit 1070.The detection circuit 1070 can utilize one or more of the followingsensing technologies, without limitation: optical; acoustical; imaging;ultrasound; infrared; or magnetic. The detection circuit 1070 caninclude an interrogation signal emitter 1072 that generatesinterrogation signals (acoustic, optical, magnetic, etc.) for purposesof determining when the stopper 1068 has reached its end position, whichcorresponds to the “end of reservoir” state. In some embodiments, thestopper 1068 can include an index feature that can be quickly and easilydetected by the detection circuit 1070 when the stopper 1068 reaches itsend position. Depending on the particular implementation, the indexfeature can be, without limitation: a visible marking; a physicalfeature such as an indentation; a colored region; an electrically,magnetically, or inductively detectable sensor element; or the like.

The detection circuit 1070 can take appropriate action when itdetermines that the stopper 1068 has reached the endpoint (or is nearthe endpoint). For example, the detection circuit 1070 can initiate analert, an alarm, or a message intended for the user or a caregiver.Moreover, the detection circuit 1070 can be suitably configured tomonitor the movement (or lack thereof) of the stopper 1068 duringoperation of the fluid pump mechanism 1064 to determine whether or notthe stopper 1068 is traveling in an expected and ordinary manner inresponse to pumping cycles. In this regard, the detection circuit 1070can be utilized to check whether or not the stopper 1068 is frozen inthe barrel 1066, whether or not the movement of the stopper 1068 isimpeded, or the like.

Upstream Occlusion Detection: Methodology 2

The upstream occlusion detection methodology presented in this sectionrelies on a mechanical switch to detect when the stopper of the fluidreservoir it at or near its end position. In this regard, FIG. 34 is asimplified diagram of an exemplary embodiment of an end of reservoirdetection system that implements a mechanical switch concept. Theembodiment depicted in FIG. 34 employs an outlet conduit 1080 as onecomponent of a switch 1082. The outlet conduit 1080 has an inlet end1084 that cooperates with a fluid reservoir 1086, an outlet end 1088 influid communication with a fluid pump mechanism (not shown), and aswitch contact section 1090 between the inlet end 1084 and the outletend 1088. The fluid reservoir 1086 provides medication fluid to thefluid pump mechanism in the manner described in the previous section.The manner in which the fluid pump mechanism functions will not beredundantly described in detail here.

The inlet end 1084 of the outlet conduit 1080 is designed to penetrate aseptum 1092 of the fluid reservoir 1086. The inlet end 1084 enters thebarrel of the fluid reservoir 1086 to establish fluid communication withthe medication fluid inside the barrel. As explained in the immediatelypreceding section, a stopper 1094 of the fluid reservoir 1086 is pulledtoward the inlet end 1084 during pumping cycles. Eventually, the stopper1094 reaches the end position shown in FIG. 34. At or near the endposition, the stopper 1094 physically contacts the inlet end 1084 of theoutlet conduit 1080, and continued movement of the stopper 1094 towardits end position causes the switch contact section 1090 of the outletconduit 1080 to deflect toward a switch contact pad 1096. FIG. 34depicts the deflected state of the switch contact section 1090 in dashedlines.

The switch contact pad 1096 can be mounted to a circuit board 1098 orany suitable structure. The switch contact section 1090 of the outletconduit 1080 is formed from an electrically conductive material. Theswitch contact pad 1096 is also formed from an electrically conductivematerial. These two components cooperate to form a mechanical switch(for simplicity and clarity, the electrical connections and leads arenot shown in FIG. 34). The circuit board 1098 may be utilized with asuitably designed detection circuit that detects when the switch contactsection 1090 touches the switch contact pad 1096. In other words, thedetection circuit detects whether the switch 1082 is open or closed. Ifthe switch 1082 is open, the detection circuit determines that the fluidreservoir 1086 is not empty. Conversely, if the switch 1082 is closed,the detection circuit determines that the fluid reservoir 1086 is at the“end of reservoir” state. The detection circuit can take appropriateaction when it detects closure of the switch 1082. For example, thedetection circuit can initiate an “end of reservoir” alert, an alarm, ora message intended for the user or a caregiver.

Upstream Occlusion Detection: Methodology 3

The upstream occlusion detection methodology presented in this sectionemploys an electrically conductive fluid reservoir stopper (or a stopperhaving an electrically conductive region). In this regard, FIG. 35 is asimplified diagram of an exemplary embodiment of an end of reservoirdetection system that utilizes a conductive stopper 1102 of a fluidreservoir 1104. The fluid reservoir 1104 provides medication fluid to afluid pump mechanism of the type described above. The manner in whichthe fluid pump mechanism functions and cooperates with the fluidreservoir 1104 will not be redundantly described in detail here.

The fluid infusion device includes an outlet conduit 1106 having aninlet end 1108 and an outlet end 1110. The inlet end 1108 is designed topenetrate a septum 1112 of the fluid reservoir 1104, and the outlet end1110 is in fluid communication with the fluid pump mechanism. The inletend 1108 enters the barrel of the fluid reservoir 1104 to establishfluid communication with the medication fluid inside the barrel. Thefluid infusion device also includes an electrically conductive needle1114. The needle 1114 has a contact end 1116 that is designed topenetrate the septum 1112 for entry into the barrel of the fluidreservoir 1104. The outlet conduit 1106 and the needle 1114 areelectrically connected to a suitably configured detection circuit (notshown). For example, the needle 1114 can be connected to a negativevoltage terminal and the outlet conduit 1106 can be connected to apositive voltage terminal (or vice versa).

As explained above, the stopper 1102 of the fluid reservoir 1104 travelstoward the inlet end 1108 of the outlet conduit 1106 during pumpingcycles. Eventually, the stopper 1102 reaches the end position (shown inFIG. 35) and makes contact with the inlet end 1108 of the outlet conduit1106 and with the contact end 1116 of the needle 1114. Notably, the areaof the stopper 1102 that makes contact with the outlet conduit 1106 andthe needle 1114 is electrically conductive. In practice, the stopper1102 can be fabricated from an electrically conductive material, or anelectrically conductive film or patch can be affixed to the top of thestopper 1102. When the stopper 1102 reaches the end position shown inFIG. 35, the outlet conduit 1106 is shorted with the needle 1114. Thisaction is akin to the closing of a switch (as described in theimmediately preceding section), which can be monitored and detected bythe detection circuit. Thus, if the fluid reservoir 1104 is not empty,the stopper 1102 will not create a short across the needle 1114 and theoutlet conduit 1106. Conversely, when the stopper 1102 reaches its endposition, the needle 1114 is shorted with the outlet conduit 1106 andthe detection circuit determines that the fluid reservoir 1104 is at the“end of reservoir” state. The detection circuit can take appropriateaction when it detects this state. For example, the detection circuitcan initiate an “end of reservoir” alert, an alarm, or a messageintended for the user or a caregiver.

Upstream Occlusion Detection: Methodology 4

The upstream occlusion detection methodology presented in this sectionutilizes an excitation signal applied to the fluid reservoir todetermine the volume of fluid remaining in the reservoir. In thisregard, FIG. 36 is a simplified diagram of an exemplary embodiment of anend of reservoir detection system that can be used to analyze thecondition of a fluid reservoir 1120 of the type described previouslyherein. The fluid reservoir 1120 provides medication fluid to a fluidpump mechanism of the type described above. The manner in which thefluid pump mechanism functions and cooperates with the fluid reservoir1120 will not be redundantly described in detail here.

The fluid infusion device that hosts the fluid reservoir 1120 includes asuitably configured detection circuit (not shown) that includes,controls, or otherwise cooperates with an excitation signal generator1122 and an associated sensor 1124. The excitation signal generator 1122can be coupled to the fluid reservoir 1120 for purposes of applying anexcitation signal to the fluid reservoir 1120. The excitation signal canbe, for example, a vibration signal having a particular frequency or aparticular frequency spectrum that is suitable for measuring theresonance or other response of the fluid reservoir 1120. The resonanceof the fluid reservoir 1120 is influenced by the volume and/or mass ofthe fluid remaining in the fluid reservoir 1120. In practice, theresonance of the fluid reservoir 1120 can be empirically determined orotherwise characterized for purposes of programming the detectioncircuit. Accordingly, the detection circuit can obtain and analyze theresponse signal in an appropriate manner to determine whether or not thefluid reservoir 1120 is empty. If the response signal is indicative ofan empty reservoir, the detection circuit can take appropriate action,e.g., initiate an “end of reservoir” alert, an alarm, or a messageintended for the user or a caregiver.

Upstream Occlusion Detection: Methodology 5

The upstream occlusion detection methodology presented in this sectionuses a force sensor to measure the position of a fluid reservoirstopper. In this regard, FIG. 37 is a simplified diagram of an exemplaryembodiment of an end of reservoir detection system for a fluid reservoir1130 of a fluid infusion device. The fluid reservoir 1130 providesmedication fluid to a fluid pump mechanism of the type described above.The manner in which the fluid pump mechanism functions and cooperateswith the fluid reservoir 1130 will not be redundantly described indetail here.

The fluid infusion device that hosts the fluid reservoir 1120 includes asuitably configured detection circuit 1132 that includes, controls, orotherwise cooperates with a force sensor 1134. The force sensor 1134 canbe configured as described above with reference to FIG. 28. The forcesensor 1134 can be used to measure the force imparted by a biasingelement 1136 (such as a spring) that is coupled to the stopper 1138 ofthe fluid reservoir 1130. The tension characteristics of the biasingelement 1136 are selected such that the biasing element 1136 cannotindependently move the stopper 1138. In other words, the force appliedby the biasing element 1136 is too low to overcome the static frictionof the stopper 1138, and the biasing element 1136 is not utilized toactuate the stopper 1138 or to otherwise deliver fluid from the fluidreservoir 1130. Rather, the stopper 1138 is designed to move only inresponse to the negative fluid pressure caused by the normal operationof the fluid pump mechanism, as described in detail above. Consequently,the biasing element 1136 is strictly utilized to provide a forcemeasurement that corresponds to the position of the stopper 1138 withinthe fluid reservoir 1130.

The force measurements obtained or otherwise processed by the detectioncircuit 1132 vary in accordance with the position of the stopper 1138.When the fluid reservoir 1130 is full, the stopper 1138 is located at ornear the base end of the fluid reservoir 1130 and, therefore, the springforce detected by the force sensor 1134 is relatively high. Conversely,when the fluid reservoir 1130 is empty, the stopper 1138 is located atits end position near the neck of the fluid reservoir 1130. When thestopper 1138 is at the end position, the spring force measured by theforce sensor 1134 is relatively low. Accordingly, the detection circuit1132 can obtain and analyze the output of the force sensor 1134 in anappropriate manner to determine whether or not the fluid reservoir 1130is empty. If the measured force is indicative of an empty reservoir, thedetection circuit 1132 can take appropriate action, e.g., initiate an“end of reservoir” alert, an alarm, or a message intended for the useror a caregiver.

Upstream Occlusion Detection: Methodology 6

The upstream occlusion detection methodology presented in this sectionuses a pressure sensor to measure the position of a fluid reservoirstopper. In this regard, FIG. 38 is a simplified diagram of an exemplaryembodiment of an end of reservoir detection system for a fluid reservoir1144 of a fluid infusion device. The fluid reservoir 1144 providesmedication fluid to a fluid pump mechanism of the type described above.The manner in which the fluid pump mechanism functions and cooperateswith the fluid reservoir 1144 will not be redundantly described indetail here.

The fluid infusion device that hosts the fluid reservoir 1144 includes asuitably configured detection circuit 1146 that includes, controls, orotherwise cooperates with a pressure sensor 1148. The pressure sensor1148 is designed to detect slight changes in the pressure of a sealedvolume 1150 that is associated with the fluid reservoir 1144. In thisregard, FIG. 38 schematically depicts a vent 1152 leading from thesealed volume 1150 to the pressure sensor 1148. The vent 1152 allows thepressure sensor 1148 to monitor the pressure inside the sealed volume1150 during operation of the fluid infusion device.

The sealed volume 1150 can be defined by suitably configured structureof the fluid infusion device. The illustrated embodiment, which ismerely one possible implementation, includes a wall structure 1154 thatat least partially surrounds the base of the fluid reservoir 1144. Anairtight sealing element 1156 (such as an o-ring or a gasket) can beused to seal the wall structure 1154 against the outer surface of thefluid reservoir 1144. It should be appreciated that the sealed volume1150 can be defined in any appropriate way, using additional structuresor components if so desired. Moreover, the shape and size of the sealedvolume 1150 can vary from one embodiment to another.

The pressure measurements obtained or otherwise processed by thedetection circuit 1146 vary in accordance with the position of thestopper 1158 of the fluid reservoir 1144. In practice, the system isdesigned and configured such that the sealed volume 1150 does notadversely influence the normal operation of the fluid infusion device.For example, the sealed volume 1150 should not impede the movement ofthe stopper 1158, which is caused by fluid intake strokes of the fluidpump mechanism.

When the fluid reservoir 1144 is full, the stopper 1158 is located at ornear the base end of the fluid reservoir 1144 and, therefore, the sealedvolume 1150 is relatively small. Consequently, the pressure obtainedfrom the pressure sensor 1148 will be relatively high. Conversely, whenthe fluid reservoir 1144 is empty, the stopper 1158 is located at itsend position near the neck of the fluid reservoir 1144. When the stopper1158 is at the end position, the sealed volume 1150 is relatively largeand, therefore, the pressure obtained from the pressure sensor 1148 willbe relatively low. Accordingly, the detection circuit 1146 can obtainand analyze the output of the pressure sensor 1148 in an appropriatemanner to determine whether or not the fluid reservoir 1144 is empty. Ifthe measured pressure of the sealed volume 1150 is indicative of anempty reservoir, the detection circuit 1146 can take appropriate action,e.g., initiate an “end of reservoir” alert, an alarm, or a messageintended for the user or a caregiver.

Upstream Occlusion Detection: Methodology 7

The upstream occlusion detection methodology presented in this sectionmeasures an inductance to determine the position of a fluid reservoirstopper. In this regard, FIG. 39 is a simplified diagram of an exemplaryembodiment of an end of reservoir detection system for a fluid reservoir1162 of a fluid infusion device. The fluid reservoir 1162 providesmedication fluid to a fluid pump mechanism of the type described above.The manner in which the fluid pump mechanism functions and cooperateswith the fluid reservoir 1162 will not be redundantly described indetail here.

The fluid reservoir 1162 is provided with a stopper 1164 having anelectrically conductive target 1166 integrated therein (or affixedthereto). Although the target 1166 is shown in FIG. 39, it can insteadbe incorporated into the body of the stopper 1164 and, therefore, behidden from view. The shape, size, and configuration of the target 1166can differ from that shown in FIG. 39, which merely shows the target1166 in schematic form. The target 1166 cooperates with an electricallyconductive coil element 1168 that resides outside of, but in closeproximity to, the fluid reservoir 1162. The fluid infusion device thathosts the fluid reservoir 1162 includes a suitably configured detectioncircuit 1170 that includes, controls, or otherwise communicates with thecoil element 1168. More specifically, the detection circuit 1170 isconnected to the terminals of the coil element 1168 such that thedetection circuit 1170 can monitor and measure the electrical inductanceof the coil element 1168 during operation of the fluid infusion device.

The target 1166 and the coil element 1168 are suitably configured suchthat the inductance of the coil element 1168 varies (in a measurablemanner) as a function of the position of the stopper 1164. Accordingly,the detection circuit 1170 observes a variable inductance as the stopper1164 travels from the base of the fluid reservoir 1162 to the endposition. The measured inductance can be correlated to the position ofthe stopper 1164, and the inductance corresponding to the end positionof the stopper 1164 can be characterized for purposes of detecting theend of reservoir state. If the measured inductance of the coil element1168 is indicative of an empty reservoir, the detection circuit 1170 cantake appropriate action, e.g., initiate an “end of reservoir” alert, analarm, or a message intended for the user or a caregiver.

Upstream Occlusion Detection: Methodology 8

The upstream occlusion detection methodology presented in this sectionmeasures a capacitance to determine the position of a fluid reservoirstopper. In this regard, FIG. 40 is a simplified diagram of an exemplaryembodiment of an end of reservoir detection system for a fluid reservoir1176 of a fluid infusion device. The fluid reservoir 1176 providesmedication fluid to a fluid pump mechanism of the type described above.The manner in which the fluid pump mechanism functions and cooperateswith the fluid reservoir 1176 will not be redundantly described indetail here.

The system described here employs a detection circuit 1178 to measurethe capacitance between a first capacitor electrode 1180 and a secondcapacitor electrode 1182. Notably, the capacitance measured by thedetection circuit 1178 is a function of the amount of fluid remaining inthe fluid reservoir 1176. Consequently, the capacitance measured by thedetection circuit 1178 is also a function of the position of the stopper1184 of the fluid reservoir 1176.

FIG. 40 schematically depicts the electrodes 1180, 1182 for purposes ofthis description. In practice, the electrodes 1180, 1182 can beintegrated into or attached to the barrel of the fluid reservoir 1176 ina way that accommodates electrical coupling to the detection circuit1178. In certain embodiments, the electrodes 1180, 1182 are located on astructure (such as a circuit board) that is held in close proximity tothe installed location of the fluid reservoir 1176. The electrodes 1180,1182 can be realized as conductive traces, metallic films, or the like.

The detection circuit 1178 is connected to the electrodes 1180, 1182such that the detection circuit 1178 can monitor and measure thecapacitance between the electrodes 1180, 1182 during operation of thefluid infusion device. As the fluid gets depleted from the fluidreservoir 1176, the capacitance between the electrodes 1180, 1182 varies(in a detectable manner), due to the changing dielectric properties ofthe fluid reservoir 1176. Accordingly, the detection circuit 1178observes a variable capacitance as the fluid exits the fluid reservoir1176. The measured capacitance can be correlated to the position of thestopper 1184 and/or to the amount of fluid remaining in the fluidreservoir 1176, and the capacitance corresponding to the end position ofthe stopper 1184 can be characterized for purposes of detecting the endof reservoir state. If the measured capacitance is indicative of anempty reservoir, the detection circuit 1178 can take appropriate action,e.g., initiate an “end of reservoir” alert, an alarm, or a messageintended for the user or a caregiver.

Upstream Occlusion Detection: Methodology 9

The upstream occlusion detection methodology presented in this sectionassumes that the fluid infusion device uses a fluid pump mechanism ofthe type described above. The methodology measures or calculates theaxial velocity of the rotor as it travels during the fluid expulsioncycle and determines whether or not an upstream occlusion (e.g., the endof the fluid reservoir) as occurred. In this regard, FIG. 41 is aschematic block diagram of an exemplary embodiment of an end ofreservoir detection system 1200 that can be implemented in a fluidinfusion device having a rotary fluid pump mechanism. For the sake ofclarity and simplicity, the fluid pump mechanism and the fluid reservoirare not shown in FIG. 41. Moreover, the manner in which the fluid pumpmechanism functions and cooperates with the fluid reservoir will not beredundantly described in detail here.

The system 1200 includes, without limitation: a detection circuit 1202;an axial position sensor 1204 (or sensing system); and an angularposition sensor 1206 (or sensing system). The axial position sensor 1204is designed and configured to obtain axial position data of the rotor,where the axial position data indicates the axial position ordisplacement of the rotor during operation of the fluid pump mechanism.The operating principle of the axial position sensor 1204 may vary fromone embodiment to another. In this regard, the axial position sensor1204 can leverage any of the position detection techniques andmethodologies described herein, including any of those previouslydescribed with reference to FIGS. 22-31, without limitation. The angularposition sensor 1206 is designed and configured to obtain angularposition data of the rotor, where the angular position data indicatesthe rotational position of the rotor, relative to any convenientreference point. In practice, the angular position of the rotor can beexpressed in degrees or in any appropriate units that correspond toangular measurement. In certain embodiments, the angular position sensor1206 may be realized as a digital encoder or counter that monitors theoperation of the drive motor, which in turn rotates the rotor.

Regardless of the manner in which the axial position sensor 1204 and theangular position sensor 1206 are implemented, the respective sensor dataor information is obtained by the detection circuit 1202 for processingand analysis. More specifically, the detection circuit 1202 can processthe sensor data to determine whether or not an occlusion upstream of thefluid pump mechanism has occurred. The determination is based on certaindetectable characteristics of the sensor data, wherein the detectioncircuit 1202 can determine whether the fluid pump mechanism is operatingas expected to draw fluid in from the fluid reservoir and expel thefluid for delivery to the patient, or whether an upstream occlusion ispreventing the fluid pump mechanism from drawing in fluid. As mentionedpreviously, an upstream occlusion may be detected when an inlet fluidflow path is blocked, or when the fluid reservoir is empty (and thestopper of the reservoir has reached its end position).

The detection circuit 1202 calculates or otherwise obtains the axialvelocity of the rotor during the fluid expulsion cycle. Referring againto FIG. 15, the section 820 of the plot represents the fluid expulsionperiod, during which the rotor normally “snaps back” into the statorunder the force of the biasing element. The velocity of the rotor duringthis period can be characterized and predicted under normal and expectedoperating conditions. It should be understood that the slope of thesection 820 is indicative of the axial velocity of the rotor (a gradualslope corresponds to lower velocity, and a steeper slope corresponds tohigher velocity). If an upstream occlusion is present (e.g., the fluidreservoir is empty and the stopper of the reservoir has reached its endposition), then the fluid pump mechanism will pull on a vacuum.Consequently, during the fluid intake period (corresponding to thesection 816 of the plot in FIG. 15) the vacuum creates additional forcein the same direction of the biasing force. This additional forceincreases the axial velocity of the rotor during the fluid expulsioncycle.

FIG. 42 is a graph that includes a plot 1210 of rotor axial positionversus rotor angular position for an upstream occlusion condition. FIG.42 also includes a plot 1212 that corresponds to the normal and expectedoperating condition in the absence of any occlusion. As FIG. 42demonstrates, the two plots 1210, 1212 exhibit roughly the samecharacteristics during the fluid intake period 1214 of the pumpingcycle. During the fluid expulsion period 1216 of the pumping cycle,however, the two plots 1210, 1212 deviate from one another. As explainedabove, the plot 1212 is characterized by a more gradual slope during theexpulsion period 1216; this gradual slope is indicative of a nominalaxial velocity of the rotor. In contrast, the plot 1210 is characterizedby a steeper slope during the expulsion period 1216. The steeper slopeis indicative of higher axial velocity of the rotor during this time.Again, the vacuum conditions created by an occlusion upstream of thefluid pump mechanism increase the axial velocity of the rotor during thefluid expulsion period (relative to the nominal axial velocityexperienced during normal fluid delivery operations).

The detection circuit 1202 is suitably configured and programmed toanalyze the collected axial position and angular position sensor data ina way that is consistent with the comparison visualized in FIG. 42. Forexample, the detection circuit 1202 can calculate an average or maximumrotor axial velocity during the fluid expulsion period and compare thecalculated velocity to a predetermined threshold axial velocity value.If the calculated axial velocity exceeds the threshold value, then thedetection circuit 1202 can declare that an upstream occlusion has beendetected. Notably, the detection circuit 1202 can consider the angularposition data to determine the timing of the pumping cycle, such thatthe axial velocity of the rotor is analyzed during the fluid expulsionphase of the cycle (rather than at other times). The detection circuit1202 can be programmed as needed to accurately characterize the axialvelocity behavior of the rotor during the fluid expulsion period. Inthis regard, under normal operating conditions the fluid expulsionperiod is characterized by a nominal axial velocity of the rotor, andunder upstream occlusion conditions the fluid expulsion period ischaracterized by a different axial velocity of the rotor, which ishigher than the nominal axial velocity of the rotor.

It should be appreciated that the detection circuit 1202 can make itsdetermination using any suitable methodology or algorithm. For example,the detection circuit 1202 can determine the axial position of the rotoras a function of the angular rotation of the rotor, calculate the slopeof the response (similar to that depicted in FIG. 42), and compare thecalculated slope against a predetermined threshold slope value. Inalternative embodiments, the detection circuit 1202 can leverageaccelerometer data to directly measure the velocity of the rotor as itmoves toward the stator during the fluid expulsion period, and comparethe measured velocity against a threshold value. These and othertechniques are contemplated by this disclosure.

Upstream Occlusion Detection: Methodology 10

The upstream occlusion detection methodology presented in this sectionassumes that the fluid infusion device uses a fluid pump mechanism ofthe type described above, i.e., one having a stator and a cooperatingrotor driven by a drive motor. The upstream occlusion detectionmethodology presented in this section analyzes the motor current of thedrive motor to determine the operating condition or state of the fluidinfusion device. Referring again to FIG. 15, one pumping cycle includesa fluid intake period (represented by the section 816 of the plot), abrief dwell period (represented by the section 818 of the plot), a fluidexpulsion period (represented by the section 820 of the plot), andanother dwell period (represented by the section 822 of the plot). Asexplained above with reference to FIGS. 5-15: the rotor cam element 722travels along the stator cam element 706 during the fluid intake periodand during the dwell period corresponding to the section 818 of theplot; the rotor cam element 722 disengages from the stator cam element706 and moves toward the reference surface 736 during the fluidexpulsion period; and the rotor cam element 722 travels along thereference surface 736 during the dwell period corresponding to thesection 822 of the plot. Continued rotation of the rotor results inrepetition of this pumping cycle.

The methodology described in this section assumes that the drive motor138 is a DC motor, and that the current consumption of the drive motor138 can be monitored and measured as it drives the rotor. It is wellestablished that the current consumption of a DC motor is proportionalto the output torque and the rotational speed (as torque increases, thecurrent draw increases and the rotational speed decreases). Thus, whenthe rotor cam element 722 is traveling on the reference surface 736 andthe applied biasing force is lower (the sections 814, 822 of the plot inFIG. 15), the motor current is somewhat stable, flat, and relativelylow. In contrast, when the rotor cam element 722 is engaged with thestator cam element 706, the biasing spring force increases, which inturn increases the friction between the cam elements. The net effect isan increase in drive current consumption and torque output from thedrive motor. The drive current peaks when the rotor cam element 722reaches the plateau of the stator cam element 706, and then graduallydecreases as the rotor cam element 722 continues traveling across theplateau. After the rotor cam element 722 disengages from the stator camelement 706 (i.e., the rotor cam element 722 falls off the plateau), thedrive current returns to its relatively low and stable baseline level.

The fluid infusion device can include a suitably configured detectioncircuit that monitors and analyzes the current of the drive motor. Thecurrent can be analyzed as a function of time, angular position of therotor, motor position, or the like. The detection circuit can comparethe measured motor current against saved current profiles or responsecurves to determine whether the fluid pump mechanism is operating in anormal and expected manner, whether an upstream occlusion has occurred,whether a downstream occlusion has occurred, or the like. For example,if the fluid reservoir is empty (or if the upstream fluid flow path isblocked), then the motor current will exhibit measurably differentcharacteristics than that described above. In this regard, the vacuumcreated by an empty reservoir or an upstream occlusion will increase theoutput torque during the fluid intake period (because the drive motor138 must overcome the force created by the vacuum). Thus, the measuredmotor current will exhibit a steeper rise and a higher maximum valueduring the fluid intake period, relative to the normal motor currentcharacteristics associated with non-occluded operation of the fluid pumpmechanism. The detection circuit can be designed to take appropriateaction if it observes this type of characteristic difference in themeasured motor current. It should be appreciated that the methodologypresented in this section can also be utilized to detect the presence ofdownstream occlusions if so desired.

Upstream Occlusion Detection: Methodology 11

The occlusion detection methodology presented in this section assumesthat the fluid infusion device uses a fluid pump mechanism of the typegenerally described above with reference to FIGS. 5-14. The timingrelated to the opening and closing of the valves, however, is slightlydifferent to accommodate occlusion detection. Consequently, the plotsdepicted in FIG. 15 and FIG. 16 do not apply to the embodimentspresented here. Moreover, at least one of the embodiments presented inthis section can be utilized for downstream occlusion detection inaddition to (or in lieu of) upstream occlusion detection.

The embodiment previously described with reference to FIG. 15 employsvalve timing such that the second valve (i.e., the outlet valve) openswhen the stator cam element disengages the rotor cam element, orimmediately before the stator cam element disengages the rotor camelement. In other words, the angular position of the trailing end of therotor cam element corresponds to the right end of the section 818 of theplot shown in FIG. 15. Consequently, both valves remain closed duringmost of the section 818, and the second valve opens in conjunction withthe stator cam element disengaging the rotor cam element.

In contrast to the previously described valve timing, the embodimentsdescribed in this section utilize a modified valve timing that delaysthe opening of the second valve. In this regard, FIG. 43 is a graph thatincludes plots of rotor axial position versus rotor angular position forvarious operating conditions of a fluid pump mechanism. In FIG. 43, aregion 1300 corresponds to a first period during which the first/inletvalve (V1) is open and the second/outlet valve (V2) is closed, theregion 1302 corresponds to a second period during which V1 is closed andV2 is open, and the region 1304 corresponds to a third period duringwhich V1 is open and V2 is closed. The gaps between these regionscorrespond to periods during which both valves are closed.

FIG. 43 also schematically depicts the reference surface 1306 of a rotor1308; the reference surface 1306 is rendered in a straight line (ratherthan a circle as depicted in FIG. 44) aligned with the rotor angle axisof the graph. For ease of illustration, FIG. 44 does not depict theendcap or surrounding structure of the rotor 1308. The rotor 1308includes a rotor cam element 1310 having a variable height that risesfrom the reference surface 1306, as described in detail above withreference to FIGS. 11-14. The illustrated embodiment of the rotor 1308also includes a first (leading) sensor contact element 1312 located onor integrated with the reference surface 1306, and a second (trailing)sensor contact element 1314 located on or integrated with the referencesurface 1306. As will become apparent from the following description,the second sensor contact element 1314 is utilized to support downstreamocclusion detection.

The first sensor contact element 1312 is located in a region that isunoccupied by the rotor cam element 1310. More specifically, the firstsensor contact element 1312 is located at an angular position thatfollows the upper (trailing) edge 1316 of the rotor cam element 1310. Asshown in FIG. 44, the first sensor contact element 1312 can bepositioned on the reference surface 1306 immediately following the rotorcam element 1310. The second sensor contact element 1314 is also locatedin a region that is unoccupied by the rotor cam element 1310. The secondsensor contact element 1314 is located at an angular position thatfollows the first sensor contact element 1312. As shown in FIG. 43 andFIG. 44, the first and second sensor contact elements 1312, 1314 areseparated by a gap having a size that is dictated by the desired valvetiming characteristics and the desired occlusion detectionfunctionality.

Referring again to FIG. 43, the angular position 1320 corresponds to thelower (leading) edge 1322 of the rotor cam element 1310, and the angularposition 1324 corresponds to the upper (trailing) edge 1316 of the rotorcam element 1310. The angular position 1326 corresponds to the beginningof the plateau 1328 of the rotor cam element 1310, i.e., the flat andhighest section of the rotor cam element 1310. Accordingly, the section1330 of the plot corresponds to the fluid intake period of the fluidpump mechanism, and the section 1332 of the plot corresponds to a dwellperiod during which the stator cam element resides on the plateau 1328of the rotor cam element 1310. The right end of the section 1332corresponds to the upper (trailing) edge 1316 of the rotor cam element1310. Notably, the rotor cam element 1310 disengages the stator camelement at a time when both the inlet valve and the outlet valve areclosed, and both valves remain closed for a short time thereafter. Thisbrief “valve delay” period is represented by the section 1334 of theplot. The valve delay period corresponds to a time (or an angle ofrotation) that begins with the end of the rotor cam element 1310 andends with the opening of the outlet valve.

The angular positioning of the first sensor contact element 1312 on therotor 1308 corresponds to a valve state that occurs after the inletvalve closes for a current pumping cycle, and before the outlet valveopens for the current pumping cycle. FIG. 43 schematically illustratesthis feature—the rotor angle associated with the position of the firstsensor contact element 1312 corresponds to a period during which both ofthe valves are closed. In contrast, the angular positioning of thesecond sensor contact element 1314 on the rotor 1308 corresponds to adifferent valve state that occurs after the outlet valve closes for thecurrent pumping cycle, and before the inlet valve opens for a nextpumping cycle.

The sensor contact elements 1312, 1314 cooperate with a suitablyconfigured sensing element or arrangement and a detection circuit, whichdetects when the sensing element makes contact with the sensor contactelements 1312, 1312. The sensing element and related features andfunctionality described above with reference to FIGS. 18 and 19 can alsobe utilized with the embodiment described here. As explained above, asensing element on the stator can be utilized to determine whether ornot the stator cam element makes contact with the first sensor contactelement 1312, the second sensor contact element 1314, or both. In thisway, the detection circuit can monitor the characteristics of adetection signal obtained from the sensing element in response to theangular position of the rotor to determine a current operating conditionof the fluid pump mechanism. For example, the sense pattern observed bythe detection circuit may be indicative of normal operating conditionsor a fault condition (such as a downstream occlusion, an upstreamocclusion, an empty fluid reservoir, or the like). If the detectioncircuit detects a fault condition, then it can initiate or generate analert, an alarm, a warning message, or take any appropriate type ofaction.

The solid plot in FIG. 43 corresponds to the behavior of the fluid pumpmechanism under normal and expected operating conditions. Under thesenormal operating conditions, both valves remain closed for the periodrepresented by the section 1334 of the plot. During this period, theaxial position of the rotor remains substantially stable (at or near itshighest point) even though the stator cam element has disengaged therotor cam element. The closed state of the output valve and the presenceof fluid in the fluid pump mechanism inhibits axial displacement of therotor during this period. As soon as the output valve opens, however,the rotor is urged toward the stator until it reaches the nominalbaseline position.

The dashed line plot in FIG. 43 corresponds to the behavior of the fluidpump mechanism under upstream occlusion conditions, which may be causedby a fluid line blockage upstream of the inlet valve or an empty fluidreservoir. In the presence of an upstream occlusion, the fluid pumpmechanism pulls on a vacuum without drawing in fluid. The vacuumconditions created by the upstream occlusion create negative pressure,which allows the rotor cam element 1310 to move toward the referencesurface 1306 even though the outlet valve is closed. This negativepressure causes the rotor to snap back into place as soon as the statorcam element disengages the rotor cam element (even though both valvesare closed). Thus, the axial displacement of the rotor quickly decreasesand reaches its nominal baseline level. The valve delay periodassociated with the section 1334 of the plot can be engineered as neededto accommodate upstream occlusion detection, as described in more detailbelow. The axial displacement of the rotor remains at the baseline leveluntil the next fluid intake cycle.

The dotted line plot in FIG. 43 corresponds to the behavior of the fluidpump mechanism under downstream occlusion conditions, which may becaused by a fluid line blockage downstream of the outlet valve. In thepresence of a downstream occlusion, the fluid pump mechanism cannotexpel fluid as usual. Consequently, the axial displacement of the rotorremains relatively high until the inlet valve opens to accommodatebackflow. Shortly thereafter, however, the next fluid intake cyclecauses the axial displacement to increase again. Notably, the axialdisplacement of the rotor remains at or near its highest level evenduring the period represented by the section 1334 of the plot. Duringthis period, the axial position of the rotor remains substantiallystable (at or near its highest point) even though the stator cam elementhas disengaged the rotor cam element.

The behavior of the fluid pump mechanism under normal and occludedconditions can be characterized such that the sensor contact elements1312, 1314 can be sized and positioned in an appropriate manner. Forexample, under normal operating conditions, the sensing element on thestator cam element makes no contact with the first sensor contactelement 1312 because the rotor remains axially displaced from the statorthroughout the angular position that corresponds to the location of thefirst sensor contact element 1312 on the reference surface 1306.Moreover, under normal operating conditions, the sensing elementcontacts the second sensor contact element 1314 once per pumping cyclebecause the rotor resides at its baseline axial position throughout theangular position that corresponds to the location of the second sensorcontact element 1314 on the reference surface 1306. Accordingly, undernormal operating conditions, the detection circuit will detect contactwith only the second sensor contact element 1314 for each pumping cycle.

Under upstream occlusion conditions (including an end of reservoir stateor a condition where the reservoir stopper has seized), the sensingelement contacts both sensor contact elements 1312, 1314 once perpumping cycle. More specifically, the sensing element contacts the firstsensor contact element 1312 shortly after the rotor cam element 1310disengages the stator cam element (and at a time when both valves areclosed) and, thereafter, the sensing element contacts the second sensorcontact element 1314. The detection circuit can determine or declarethat an upstream occlusion has occurred based on the sensing elementcontacting the first and second sensor contact elements 1312, 1314.Alternatively, the detection circuit can determine or declare that anupstream occlusion has occurred based on the sensing element contactingthe first sensor contact element 1312 alone. Indeed, the second sensorcontact element 1314 need not be employed for purposes of upstreamocclusion detection.

Under downstream occlusion conditions, the sensing element makes nocontact with either of the sensor contact elements 1312, 1314. Rather,the downstream occlusion prevents the stator cam element from reachingthe reference surface 1306 of the rotor in the angular position range ofthe sensor contact elements 1312, 1314. As shown in FIG. 43, when thedownstream fluid path is blocked, the sensing element does not reach thereference surface 1306 (if at all) until shortly after the outlet valveopens. Accordingly, the detection circuit can determine or declare thata downstream occlusion has occurred based on the sensing element makingno contact with the sensor contact elements 1312, 1314.

In practice, the detection circuit described in this section can bedesigned to observe signal characteristics that result from interactionbetween the sensing element and the sensor contact elements 1312, 1314.In this regard, a different signal pattern will be generated for eachrevolution of the rotor, which corresponds to one pumping cycle. Thedetection circuit can monitor the obtained sensor signal pattern todetermine the current operating condition/state of the fluid pumpmechanism. For the embodiment presented in this section, a detectedpattern of S1=LOW+S2=HIGH indicates normal operation (where S1 is thestate of the first sensor contact element 1314 and S2 is the state ofthe second sensor contact element). A detected pattern ofS1=HIGH+S2=HIGH indicates an upstream occlusion condition, and adetected pattern of S1=LOW+S2=LOW indicates a downstream occlusioncondition. Alternatively, the detection circuit can simply count thenumber of detected “hits” during each rotation of the rotor 1308,without necessarily keeping track of which sensor contact element 1312,1314 was contacted: only one count indicates normal operation; twocounts indicates an upstream occlusion; and zero counts indicates adownstream occlusion. This simple encoding scheme makes it easy for thedetection circuit to distinguish the three operating conditions ofinterest.

For the embodiment depicted in FIG. 44, the sensor contact elements1312, 1314 are located on the reference surface 1306 of the rotor 1308.Moreover, the embodiment of FIG. 44 cooperates with a sensing elementincorporated into the stator cam element (of the type described abovewith reference to FIGS. 18 and 19). In contrast, FIG. 45 and FIG. 46depict an alternative embodiment having a different arrangement ofsensor contact elements. In this regard, FIG. 45 is a perspective endview of an exemplary embodiment of a rotor 1400 of a fluid pumpmechanism, and FIG. 46 is a side view that depicts the rotor 1400cooperating with a compatible stator 1402 of the fluid pump mechanism.The basic configuration, design, and functionality of the rotor 1400 andthe stator 1402 are similar to that described previously with referenceto FIGS. 5-14, and common features and aspects will not be redundantlydescribed in detail here. However, the valve timing and arrangement ofthe stator cam element (not shown in FIG. 46) and the rotor cam element1404 are similar to that described previously in this section withreference to FIG. 43 and FIG. 44.

The rotor 1400 includes an endcap 1406 having an exposed rim 1408 thatfaces a counterpart flange 1410 of the stator 1402. The referencesurface 1412 of the rotor 1400 and the rotor cam element 1404 arelocated inside (underneath) the endcap 1406. The rotor 1400 alsoincludes a first sensor contact element 1414 and a second sensor contactelement 1416, both of which are located on the rim 1408 or areincorporated into the rim 1408. The shape, size, and location of thefirst sensor contact element 1414 are consistent with that describedabove for the first sensor contact element 1312 of the rotor 1308.Likewise, the shape, size, and location of the second sensor contactelement 1416 are consistent with that described above for the secondsensor contact element 1314 of the rotor 1308. Placement of the sensorcontact elements 1414, 1416 on the rim 1408 instead of the referencesurface 1412 merely shifts their axial positions; their angularpositions relative to the rotor cam element 1404 and relative to thetiming of the valves remains effectively the same as that describedabove. Thus, the first sensor contact element 1414 is located at anangular position that follows the upper edge 1420 of the rotor camelement 1404, and the second sensor contact element 1416 is located atan angular position that follows the first sensor contact element 1414.It should be appreciated that the plots shown in FIG. 43 for normaloperating conditions, upstream occlusion conditions, and downstreamocclusion conditions also apply to the embodiment depicted in FIG. 45and FIG. 46.

The sensing element can be located on, incorporated into, or otherwisecarried by the stator 1402. The illustrated embodiment employs first andsecond conductive spring tabs 1424, 1426, which are located on theflange 1410 of the stator 1402. The conductive spring tabs 1424, 1426extend toward the rim 1408 of the rotor 1400, and are sized and arrangedto make physical and electrical contact with the sensor contact elements1414, 1416 when the axial position of the rotor 1400 is at the nominalbaseline position, and when the angular position of the rotor 1400relative to the stator 1402 aligns the conductive spring tabs 1424, 1426with the sensor contact elements 1414, 1416. Although not shown in FIG.46, each conductive spring tab 1424, 1426 can be electrically coupled tothe detection circuit to accommodate the detection methodology presentedhere. In this regard, the conductive spring tabs 1424, 1426 can beconnected to the detection circuit in a manner similar to that describedabove with reference to FIG. 19. Thus, the detection circuit candetermine when the two conductive spring tabs 1424, 1426 have beenshorted together by one of the sensor contact elements 1414, 1416. Forexample, FIG. 46 depicts the rotor 1400 and the stator 1402 at a momentwhen the conductive spring tabs 1424, 1426 are physically andelectrically coupled to the sensor contact element 1414.

It should be appreciated that the embodiment described above withreference to FIGS. 17-19 can be alternatively configured to useconductive spring tabs and a sensor contact element 870 on the rim 882of the endcap 858. In other words, the sensor arrangement shown in FIG.45 and FIG. 46 can be deployed in an equivalent manner with the rotor852 and the stator 854

While at least one exemplary embodiment has been presented in theforegoing detailed description, it should be appreciated that a vastnumber of variations exist. It should also be appreciated that theexemplary embodiment or embodiments described herein are not intended tolimit the scope, applicability, or configuration of the claimed subjectmatter in any way. Rather, the foregoing detailed description willprovide those skilled in the art with a convenient road map forimplementing the described embodiment or embodiments. It should beunderstood that various changes can be made in the function andarrangement of elements without departing from the scope defined by theclaims, which includes known equivalents and foreseeable equivalents atthe time of filing this patent application.

What is claimed is:
 1. A fluid pump mechanism comprising: a statorcomprising a stator cam element having a stator cam surface; a rotorcomprising a reference surface and a rotor cam element having a variableheight rising from the reference surface, the rotor cam elementcooperating with the stator cam element to axially displace the rotor,relative to the stator, as a function of angular position of the rotor;a biasing element that provides a biasing force to urge the rotor camelement toward the stator cam element and toward the reference surface;and a detection circuit to process axial position data and angularposition data of the rotor, and to determine that an upstream occlusionhas occurred based on detectable characteristics of the axial andangular position data, wherein the detection circuit calculates axialvelocity of the rotor, based on the axial position data, during a fluidexpulsion period of the fluid pump mechanism, the fluid expulsion periodindicated by the angular position data, and wherein the detectioncircuit determines that an upstream occlusion has occurred when thecalculated axial velocity of the rotor exceeds a threshold axialvelocity value.
 2. The fluid pump mechanism of claim 1, wherein: thedetection circuit initiates an alert, alarm, or warning message inresponse to determining that an upstream occlusion has occurred.
 3. Thefluid pump mechanism of claim 1, wherein, under normal operatingconditions: a complete rotation of the rotor corresponds to one pumpingcycle comprising a fluid intake period followed by the fluid expulsionperiod; during the fluid intake period, the stator cam element is incontact with the rotor cam element; during the fluid expulsion period,the rotor cam element disengages the stator cam element, and the biasingelement axially displaces the rotor such that the rotor cam elementmoves toward the reference surface; and after the fluid expulsion periodand before a next fluid intake period, the stator cam element is incontact with the reference surface.
 4. The fluid pump mechanism of claim3, wherein, under upstream occlusion conditions: vacuum conditionscreated by an occlusion upstream of the fluid pump mechanism increaseaxial velocity of the rotor during the fluid expulsion period.
 5. Thefluid pump mechanism of claim 4, wherein the upstream occlusion isassociated with an empty fluid reservoir condition.
 6. The fluid pumpmechanism of claim 1, further comprising: an axial position sensorassociated with the detection circuit, the axial position sensorobtaining the axial position data of the rotor.
 7. The fluid pumpmechanism of claim 1, further comprising: an angular position sensorassociated with the detection circuit, the angular position sensorobtaining the angular position data of the rotor.
 8. A fluid infusiondevice for delivering a medication fluid to a body, the fluid infusiondevice comprising: a fluid pump mechanism that cooperates with a fluidcartridge module, the fluid pump mechanism comprising a rotor and astator, the rotor comprising a reference surface and a rotor cam elementhaving a variable height rising from the reference surface, the statorcomprising a stator cam element having a stator cam surface, the rotorcam element cooperating with the stator cam element to axially displacethe rotor, relative to the stator, as a function of angular position ofthe rotor; a biasing element that provides a biasing force to urge therotor cam element toward the stator cam element and toward the referencesurface; a subcutaneous conduit in fluid communication with an outletvalve of the fluid pump mechanism; a drive motor coupled to actuate therotor of the fluid pump mechanism to pump medication fluid from thefluid cartridge module to the body, via the subcutaneous conduit; anaxial position sensor to obtain axial position data of the rotor duringoperation of the fluid pump mechanism; an angular position sensor toobtain angular position data of the rotor during operation of the fluidpump mechanism; and a detection circuit to process the axial and angularposition data of the rotor, and to determine that an upstream occlusionhas occurred based on detectable characteristics of the axial andangular position data, wherein the detection circuit calculates axialvelocity of the rotor, based on the axial position data, during a fluidexpulsion period of the fluid pump mechanism, the fluid expulsion periodindicated by the angular position data, and wherein the detectioncircuit determines that an upstream occlusion has occurred when thecalculated axial velocity of the rotor exceeds a threshold axialvelocity value.
 9. The fluid infusion device of claim 8, wherein: thefluid infusion device is a disposable insulin pump device; and themedication fluid comprises insulin.
 10. The fluid infusion device ofclaim 8, wherein: a complete rotation of the rotor corresponds to onepumping cycle comprising a fluid intake period followed by the fluidexpulsion period; under normal operating conditions, the fluid expulsionperiod is characterized by a first axial velocity of the rotor; andunder upstream occlusion conditions, the fluid expulsion period ischaracterized by a second axial velocity of the rotor, wherein thesecond axial velocity is higher than the first axial velocity.
 11. Thefluid infusion device of claim 10, wherein, under normal operatingconditions: during the fluid intake period, the stator cam element is incontact with the rotor cam element; during the fluid expulsion period,the rotor cam element disengages the stator cam element, and the biasingelement axially displaces the rotor such that the rotor cam elementmoves toward the reference surface; and after the fluid expulsion periodand before a next fluid intake period, the stator cam element is incontact with the reference surface.
 12. The fluid infusion device ofclaim 10, wherein, under upstream occlusion conditions: vacuumconditions created by an occlusion upstream of the fluid pump mechanismincrease axial velocity of the rotor during the fluid expulsion period.13. The fluid infusion device of claim 10, wherein: vacuum conditionscreated when the fluid reservoir is empty increase axial velocity of therotor during the fluid expulsion period.